Method for stabilization of optimal input speed in mode for a hybrid powertrain system

ABSTRACT

A method for improving drivability of the powertrain system having an accelerator control includes determining a first transmission input speed having an associated first power loss and operating said transmission using said first transmission input speed. An operational parameter relating to said accelerator control is determined and a second transmission input speed responsive to said operational parameter and having an associated second power loss is determined. The value of at least one of said first and second power loss is biased based on said operational parameter. The first power loss is compared to said second power loss subsequent to the biasing. A third transmission input speed is determined and the transmission is operated using the third transmission input speed.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.60/985,224 filed on Nov. 3, 2007, which is hereby incorporated herein byreference.

TECHNICAL FIELD

This disclosure relates generally to control systems forelectro-mechanical transmissions.

BACKGROUND

The statements in this section merely provide background informationrelated to the present disclosure and may not constitute prior art.

Known powertrain architectures include torque-generative devices,including internal combustion engines and electric machines, whichtransmit torque through a transmission device to an output member. Oneexemplary powertrain includes a two-mode, compound-split,electro-mechanical transmission which utilizes an input member forreceiving motive torque from a prime mover power source, preferably aninternal combustion engine, and an output member. The output member canbe operatively connected to a driveline for a motor vehicle fortransmitting tractive torque thereto. Electric machines, operative asmotors or generators, generate a torque input to the transmission,independently of a torque input from the internal combustion engine. Theelectric machines may transform vehicle kinetic energy, transmittedthrough the vehicle driveline, to electrical energy that is storable inan electrical energy storage device. A control system monitors variousinputs from the vehicle and the operator and provides operationalcontrol of the powertrain, including controlling transmission operatingstate and gear shifting, controlling the torque-generative devices, andregulating the electrical power interchange among the electrical energystorage device and the electric machines to manage outputs of thetransmission, including torque and rotational speed.

SUMMARY

A powertrain system has an accelerator control and includes an enginecoupled to an electro-mechanical transmission selectively operative inone of a plurality of transmission operating range states and one of aplurality of engine states. A method for improving drivability of thepowertrain system includes determining a first transmission input speedhaving an associated first power loss and operating said transmissionusing said first transmission input speed. An operational parameterrelating to said accelerator control is determined and a secondtransmission input speed responsive to said operational parameter andhaving an associated second power loss is determined. The value of atleast one of said first and second power loss is biased based on saidoperational parameter. The first power loss is compared to said secondpower loss subsequent to the biasing. A third transmission input speedis determined and the transmission is operated using the thirdtransmission input speed.

BRIEF DESCRIPTION OF THE DRAWINGS

One or more embodiments will now be described, by way of example, withreference to the accompanying drawings, in which:

FIG. 1 is a schematic diagram of an exemplary powertrain, in accordancewith the present disclosure;

FIG. 2 is a schematic diagram of an exemplary architecture for a controlsystem and powertrain, in accordance with the present disclosure;

FIGS. 3-8 are schematic flow diagrams of various aspects of a controlscheme, in accordance with the present disclosure;

FIG. 9 is a schematic power flow diagram, in accordance with the presentdisclosure;

FIG. 10 illustrates an arrangement of a first plurality of preferabilityfactors relating to a method, in accordance with the present disclosure;

FIG. 11 illustrates a combination of a plurality of preferabilityfactors, in accordance with the present disclosure;

FIG. 12 provides a graphical representation of a stabilization ofchanges of operating range of an electro-mechanical hybrid transmission,in accordance with the present disclosure;

FIG. 13 shows an alternate graphical representation of a stabilizationof changes of operating range of an electro-mechanical hybridtransmission, in accordance with the present disclosure;

FIG. 14 depicts an architecture useful in carrying out execution of achange of operating range of an electro-mechanical hybrid transmission,in accordance with the present disclosure;

FIG. 15 shows a path taken by the transmission input speed over thecourse of a change from one potential transmission operating range stateto another, in accordance with the present disclosure;

FIG. 16 illustrates variation in transmission input speed values as afunction of time for various potential operating range states of anelectro-mechanical hybrid transmission, in accordance with the presentdisclosure;

FIG. 17 shows differences in rpm values between different transmissioninput speed values at a selected point in time between various potentialoperating range states of an electro-mechanical hybrid transmission, inaccordance with the present disclosure;

FIG. 18 shows a profile of how input speeds for an electro-mechanicalhybrid transmission vary at a change in mode during resetting of afilter, in accordance with the present disclosure;

FIG. 19 illustrates one biasing cost function useful in biasing thepreferability of a potential transmission operating range state for agiven operator torque request, in accordance with the presentdisclosure;

FIG. 20 is one embodiment of a representation of the difference overtime between an operator torque request and a desirable transmissiontorque output for an exemplary transmission operating range state, inaccordance with the present disclosure;

FIG. 21 is a graphical definition of the space in which a search engineselects values for evaluation of torque outputs, in accordance with thepresent disclosure;

FIG. 22 is a 3-dimensional graphical representation of a hypotheticalcost function, in accordance with the present disclosure;

FIG. 23 is a profile of how transmission input speed over time mightappear, in accordance with the present disclosure;

FIG. 24 illustrates a smoothing effect in the transmission input speedover time, in accordance with the present disclosure;

FIG. 25 is a flow chart showing processing of data relating to theaccelerator pedal position to provide a biasing cost, in accordance withthe present disclosure; and

FIG. 26 is a flow chart showing processing of data relating to theaccelerator pedal position to provide a biasing cost, in accordance withthe present disclosure.

DETAILED DESCRIPTION

Referring now to the drawings, wherein the showings are for the purposeof illustrating certain exemplary embodiments only and not for thepurpose of limiting the same, FIG. 1 shows an exemplaryelectro-mechanical hybrid powertrain. The exemplary electro-mechanicalhybrid powertrain shown in FIG. 1 comprises a two-mode, compound-split,electro-mechanical hybrid transmission 10 operatively connected to anengine 14, and first and second electric machines (‘MG-A’) 56 and(‘MG-B’) 72. The engine 14 and first and second electric machines 56 and72 each generate power which can be transmitted to the transmission 10.The power generated by the engine 14 and the first and second electricmachines 56 and 72 and transmitted to the transmission 10 is describedin terms of input torques, referred to herein as T_(I), T_(A), and T_(B)respectively, and speed, referred to herein as N_(I), N_(A), and N_(B),respectively.

In one embodiment, the exemplary engine 14 comprises a multi-cylinderinternal combustion engine which is selectively operative in severalstates to transmit torque to the transmission 10 via an input shaft 12,and can be either a spark-ignition or a compression-ignition engine. Theengine 14 includes a crankshaft (not shown) operatively coupled to theinput shaft 12 of the transmission 10. A rotational speed sensor 11 ispreferably present to monitor rotational speed of the input shaft 12.Power output from the engine 14, comprising rotational speed and outputtorque, can differ from the input speed, N_(I), and the input torque,T_(I), to the transmission 10 due to torque-consuming components beingpresent on or in operative mechanical contact with the input shaft 12between the engine 14 and the transmission 10, e.g., a hydraulic pump(not shown) and/or a torque management device (not shown).

In one embodiment the exemplary transmission 10 comprises threeplanetary-gear sets 24, 26 and 28, and four selectively-engageabletorque-transmitting devices, i.e., clutches C1 70, C2 62, C3 73, and C475. As used herein, clutches refer to any type of friction torquetransfer device including single or compound plate clutches or packs,band clutches, and brakes, for example. A hydraulic control circuit 42,preferably controlled by a transmission control module (hereafter ‘TCM’)17, is operative to control clutch states. In one embodiment, clutchesC2 62 and C4 75 preferably comprise hydraulically-applied rotatingfriction clutches. In one embodiment, clutches C1 70 and C3 73preferably comprise hydraulically-controlled stationary devices that canbe selectively grounded to a transmission case 68. In a preferredembodiment, each of the clutches C1 70, C2 62, C3 73, and C4 75 ispreferably hydraulically applied, selectively receiving pressurizedhydraulic fluid via the hydraulic control circuit 42.

In one embodiment, the first and second electric machines 56 and 72preferably comprise three-phase AC machines, each including a stator(not shown) and a rotor (not shown), and respective resolvers 80 and 82.The motor stator for each machine is grounded to an outer portion of thetransmission case 68, and includes a stator core with electricalwindings extending therefrom. The rotor for the first electric machine56 is supported on a hub plate gear that is operatively attached toshaft 60 via the second planetary gear set 26. The rotor for the secondelectric machine 72 is fixedly attached to a sleeve shaft hub 66.

Each of the resolvers 80 and 82 preferably comprises a variablereluctance device including a resolver stator (not shown) and a resolverrotor (not shown). The resolvers 80 and 82 are appropriately positionedand assembled on respective ones of the first and second electricmachines 56 and 72. Stators of respective ones of the resolvers 80 and82 are operatively connected to one of the stators for the first andsecond electric machines 56 and 72. The resolver rotors are operativelyconnected to the rotor for the corresponding first and second electricmachines 56 and 72. Each of the resolvers 80 and 82 is signally andoperatively connected to a transmission power inverter control module(hereafter ‘TPIM’) 19, and each senses and monitors rotational positionof the resolver rotor relative to the resolver stator, thus monitoringrotational position of respective ones of first and second electricmachines 56 and 72. Additionally, the signals output from the resolvers80 and 82 are interpreted to provide the rotational speeds for first andsecond electric machines 56 and 72, i.e., N_(A) and N_(B), respectively.

The transmission 10 includes an output member 64, e.g. a shaft, which isoperably connected to a driveline 90 for a vehicle (not shown), toprovide output power, e.g., to vehicle wheels 93, one of which is shownin FIG. 1. The output power is characterized in terms of an outputrotational speed, N_(O) and an output torque, T_(O). A transmissionoutput speed sensor 84 monitors rotational speed and rotationaldirection of the output member 64. Each of the vehicle wheels 93, ispreferably equipped with a sensor 94 adapted to monitor wheel speed,V_(SS-WHL), the output of which is monitored by a control module of adistributed control module system described with respect to FIG. 2, todetermine vehicle speed, and absolute and relative wheel speeds forbraking control, traction control, and vehicle acceleration management.

The input torques from the engine 14 and the first and second electricmachines 56 and 72 (T_(I), T_(A), and T_(B) respectively) are generatedas a result of energy conversion from fuel or electrical potentialstored in an electrical energy storage device (hereafter ‘ESD’) 74. ESD74 is high voltage DC-coupled to the TPIM 19 via DC transfer conductors27. The transfer conductors 27 include a contactor switch 38. When thecontactor switch 38 is closed, under normal operation, electric currentcan flow between the ESD 74 and the TPIM 19. When the contactor switch38 is opened electric current flow between the ESD 74 and the TPIM 19 isinterrupted. The TPIM 19 transmits electrical power to and from thefirst electric machine 56 by transfer conductors 29, and the TPIM 19similarly transmits electrical power to and from the second electricmachine 72 by transfer conductors 31, in response to torque commands forthe first and second electric machines 56 and 72 to achieve the inputtorques T_(A) and T_(B). Electrical current is transmitted to and fromthe ESD 74 in accordance with commands provided to the TPIM which derivefrom such factors as including operator torque requests, currentoperating conditions and states, and such commands determine whether theESD 74 is being charged, discharged or is in stasis at any giveninstant.

The TPIM 19 includes the pair of power inverters (not shown) andrespective motor control modules (not shown) configured to receive thetorque commands and control inverter states therefrom for providingmotor drive or regeneration functionality to achieve the input torquesT_(A) and T_(B). The power inverters comprise known complementarythree-phase power electronics devices, and each includes a plurality ofinsulated gate bipolar transistors (not shown) for converting DC powerfrom the ESD 74 to AC power for powering respective ones of the firstand second electric machines 56 and 72, by switching at highfrequencies. The insulated gate bipolar transistors form a switch modepower supply configured to receive control commands. There is typicallyone pair of insulated gate bipolar transistors for each phase of each ofthe three-phase electric machines. States of the insulated gate bipolartransistors are controlled to provide motor drive mechanical powergeneration or electric power regeneration functionality. The three-phaseinverters receive or supply DC electric power via DC transfer conductors27 and transform it to or from three-phase AC power, which is conductedto or from the first and second electric machines 56 and 72 foroperation as motors or generators via transfer conductors 29 and 31,depending on commands received which are typically based on factorswhich include current operating state and operator torque demand.

FIG. 2 is a schematic block diagram of the distributed control modulesystem. The elements described hereinafter comprise a subset of anoverall vehicle control architecture, and provide coordinated systemcontrol of the exemplary hybrid powertrain described in FIG. 1. Thedistributed control module system synthesizes pertinent information andinputs, and executes algorithms to control various actuators to achievecontrol objectives, including objectives related to fuel economy,emissions, performance, drivability, and protection of hardware,including batteries of ESD 74 and the first and second electric machines56 and 72. The distributed control module system includes an enginecontrol module (hereafter ‘ECM’) 23, the TCM 17, a battery pack controlmodule (hereafter ‘BPCM’) 21, and the TPIM 19. A hybrid control module(hereafter ‘HCP’) 5 provides supervisory control and coordination of theECM 23, the TCM 17, the BPCM 21, and the TPIM 19. A user interface(‘UI’) 13 is operatively connected to a plurality of devices throughwhich a vehicle operator may selectively control or direct operation ofthe electro-mechanical hybrid powertrain. The devices present in UI 13typically include an accelerator pedal 113 (‘AP’) from which an operatortorque request is determined, an operator brake pedal 112 (‘BP’), atransmission gear selector 114 (‘PRNDL’), and a vehicle speed cruisecontrol (not shown). The transmission gear selector 114 may have adiscrete number of operator-selectable positions, including therotational direction of the output member 64 to enable one of a forwardand a reverse direction.

The aforementioned control modules communicate with other controlmodules, sensors, and actuators via a local area network (hereafter‘LAN’) bus 6. The LAN bus 6 allows for structured communication ofstates of operating parameters and actuator command signals between thevarious control modules. The specific communication protocol utilized isapplication-specific. The LAN bus 6 and appropriate protocols providefor robust messaging and multi-control module interfacing between theaforementioned control modules, and other control modules providingfunctionality such as antilock braking, traction control, and vehiclestability. Multiple communications buses may be used to improvecommunications speed and provide some level of signal redundancy andintegrity. Communication between individual control modules can also beeffected using a direct link, e.g., a serial peripheral interface(‘SPI’) bus (not shown).

The HCP 5 provides supervisory control of the powertrain, serving tocoordinate operation of the ECM 23, TCM 17, TPIM 19, and BPCM 21. Basedupon various input signals from the user interface 13 and thepowertrain, including the ESD 74, the HCP 5 generates various commands,including: the operator torque request (‘T_(O) _(—) _(REQ)’), acommanded output torque (‘T_(CMD)’) to the driveline 90, an engine inputtorque command, clutch torques for the torque-transfer clutches C1 70,C2 62, C3 73, C4 75 of the transmission 10; and the torque commands forthe first and second electric machines 56 and 72, respectively. The TCM17 is operatively connected to the hydraulic control circuit 42 andprovides various functions including monitoring various pressure sensingdevices (not shown) and generating and communicating control signals tovarious solenoids (not shown) thereby controlling pressure switches andcontrol valves contained within the hydraulic control circuit 42.

The ECM 23 is operatively connected to the engine 14, and functions toacquire data from sensors and control actuators of the engine 14 over aplurality of discrete lines, shown for simplicity as an aggregatebi-directional interface cable 35. The ECM 23 receives the engine inputtorque command from the HCP 5. The ECM 23 determines the actual engineinput torque, T_(I), provided to the transmission 10 at that point intime based upon monitored engine speed and load, which is communicatedto the HCP 5. The ECM 23 monitors input from the rotational speed sensor11 to determine the engine input speed to the input shaft 12, whichtranslates to the transmission input speed, N_(I). The ECM 23 monitorsinputs from sensors (not shown) to determine states of other engineoperating parameters which may include without limitation: a manifoldpressure, engine coolant temperature, throttle position, ambient airtemperature, and ambient pressure. The engine load can be determined,for example, from the manifold pressure, or alternatively, frommonitoring operator input to the accelerator pedal 113. The ECM 23generates and communicates command signals to control engine actuators,which may include without limitation actuators such as: fuel injectors,ignition modules, and throttle control modules, none of which are shown.

The TCM 17 is operatively connected to the transmission 10 and monitorsinputs from sensors (not shown) to determine states of transmissionoperating parameters. The TCM 17 generates and communicates commandsignals to control the transmission 10, including controlling thehydraulic circuit 42. Inputs from the TCM 17 to the HCP 5 includeestimated clutch torques for each of the clutches, i.e., C1 70, C2 62,C3 73, and C4 75, and rotational output speed, N_(O), of the outputmember 64. Other actuators and sensors may be used to provide additionalinformation from the TCM 17 to the HCP 5 for control purposes. The TCM17 monitors inputs from pressure switches (not shown) and selectivelyactuates pressure control solenoids (not shown) and shift solenoids (notshown) of the hydraulic circuit 42 to selectively actuate the variousclutches C1 70, C2 62, C3 73, and C4 75 to achieve various transmissionoperating range states, as described hereinbelow.

The BPCM 21 is signally connected to sensors (not shown) to monitor theESD 74, including states of electrical current and voltage parameters,to provide information indicative of parametric states of the batteriesof the ESD 74 to the HCP 5. The parametric states of the batteriespreferably include battery state-of-charge, battery voltage, batterytemperature, and available battery power, referred to as a range P_(BAT)_(—) _(MIN) to P_(BAT) _(—) _(MAX).

Each of the control modules ECM 23, TCM 17, TPIM 19 and BPCM 21 ispreferably a general-purpose digital computer comprising amicroprocessor or central processing unit, storage mediums comprisingread only memory (‘ROM’), random access memory (‘RAM’), electricallyprogrammable read only memory (‘EPROM’), a high speed clock, analog todigital (‘A/D’) and digital to analog (‘D/A’) circuitry, andinput/output circuitry and devices (‘I/O’) and appropriate signalconditioning and buffer circuitry. Each of the control modules has a setof control algorithms, comprising resident program instructions andcalibrations stored in one of the storage mediums and executed toprovide the respective functions of each computer. Information transferbetween the control modules is preferably accomplished using the LAN bus6 and serial peripheral interface buses. The control algorithms areexecuted during preset loop cycles such that each algorithm is executedat least once each loop cycle. Algorithms stored in the non-volatilememory devices are executed by one of the central processing units tomonitor inputs from the sensing devices and execute control anddiagnostic routines to control operation of the actuators, using presetcalibrations. Loop cycles are preferably executed at regular intervals,for example at each 3.125, 6.25, 12.5, 25 and 100 milliseconds duringongoing operation of the powertrain. However, any interval between about2 milliseconds and about 300 milliseconds may be selected.Alternatively, algorithms may be executed in response to the occurrenceof any selected event.

The exemplary powertrain shown in reference to FIG. 1 is capable ofselectively operating in any of several operating range states that canbe described in terms of an engine state comprising one of an engine onstate (‘ON’) and an engine off state (‘OFF’), and a transmission statecomprising a plurality of fixed gears and continuously variableoperating modes, described with reference to Table I, below.

TABLE I Engine Transmission Operating Applied Description State RangeState Clutches M1_Eng_Off OFF EVT Mode 1 C1 70 M1_Eng_On ON EVT Mode 1C1 70 G1 ON Fixed Gear Ratio 1 C1 70 C4 75 G2 ON Fixed Gear Ratio 2 C170 C2 62 M2_Eng_Off OFF EVT Mode 2 C2 62 M2_Eng_On ON EVT Mode 2 C2 62G3 ON Fixed Gear Ratio 3 C2 62 C4 75 G4 ON Fixed Gear Ratio 4 C2 62 C373

Each of the transmission operating range states is described in thetable and indicates which of the specific clutches C1 70, C2 62, C3 73,and C4 75 are applied for each of the operating range states. As anexample, a first continuously variable mode, i.e., EVT Mode 1, or M1, isselected by applying clutch C1 70 only in order to “ground” the outergear member of the third planetary gear set 28. The engine state can beone of ON (‘M1_Eng_On’) or OFF (‘M1_Eng_Off’). A second continuouslyvariable mode, i.e., EVT Mode 2, or M2, is selected by applying clutchC2 62 only to connect the shaft 60 to the carrier of the third planetarygear set 28. The engine state can be one of ON (‘M2_Eng_On’) or OFF(‘M2_Eng_Off’). For purposes of this description, when the engine stateis OFF, the engine input speed is equal to zero revolutions per minute(‘RPM’), i.e., the engine crankshaft is not rotating. A fixed gearoperation provides a fixed ratio operation of input-to-output speed ofthe transmission 10, i.e., N_(I)/N_(O), is achieved. For example, afirst fixed gear operation (‘G1 ’) is selected by applying clutches C170 and C4 75. A second fixed gear operation (‘G2’) is selected byapplying clutches C1 70 and C2 62. A third fixed gear operation (‘G3’)is selected by applying clutches C2 62 and C4 75. A fourth fixed gearoperation (‘G4’) is selected by applying clutches C2 62 and C3 73. Thefixed ratio operation of input-to-output speed increases with increasedfixed gear operation due to decreased gear ratios in the planetary gears24, 26, and 28. The rotational speeds of the first and second electricmachines 56 and 72, N_(A) and N_(B) respectively, are dependent oninternal rotation of the mechanism as defined by the clutching and areproportional to the input speed measured at the input shaft 12.

In response to operator input via the accelerator pedal 113 and brakepedal 112 as captured by the user interface 13, the HCP 5 and one ormore of the other control modules determine the commanded output torque,T_(CMD), intended to meet the operator torque request, T_(O) _(—)_(REQ), to be executed at the output member 64 and transmitted to thedriveline 90. Resultant vehicle acceleration is affected by otherfactors including, e.g., road load, road grade, and vehicle mass. Theoperating range state is determined for the transmission 10 based uponinputs which include a variety of operating characteristics of thepowertrain. These include the operator torque request communicatedthrough the accelerator pedal 113 and brake pedal 112 to the userinterface 13.

In some embodiments, the operating range state may be predicated on apowertrain torque demand caused by a command to operate the first andsecond electric machines 56 and 72 in an electrical energy generatingmode or in a torque generating mode. In some embodiments, the operatingrange state can be determined by an optimization algorithm or routinewhich determines a preferential selection of the operating range statebased upon inputs which may include: operator demand for power; batterystate-of-charge; and operating efficiencies of the engine 14 and thefirst and second electric machines 56, 72. The control system managestorque inputs from the engine 14 and the first and second electricmachines 56 and 72 based upon pre-selected outcome criteria embedded inthe executed selection routine, and system operation is controlledthereby to effectively manage resources commensurate with desired levelsof ESD state-of-charge and fuel delivery. Moreover, operation can bedetermined, including over-riding of any desired feature(s), based upondetection of a fault in one or more components or sub-systems. The HCP 5monitors the torque-generative devices, and determines the power outputfrom the transmission 10 required to achieve the output torque necessaryto meet the operator torque request. The ESD 74 and the first and secondelectric machines 56 and 72 are electrically-operatively coupled forpower flow therebetween. Furthermore, the engine 14, the first andsecond electric machines 56 and 72, and the electro-mechanicaltransmission 10 are mechanically-operatively coupled to transmit powertherebetween to generate a power flow to the output member 64.

Given various operating conditions possible for a motorized vehicleequipped with an electro-mechanical hybrid transmission, which includevaried environmental and road conditions such as road grade and operatortorque demands, it is generally possible for an electro-mechanicalhybrid transmission to be usefully operatively engaged potentially inmore than one operating range state, including such range statesspecified in Table I, at a given time during its operation. Moreover, itmay be true that for every change in road grade, throttle opening, andbrake pedal depression that a motorized vehicle comprising anelectro-mechanical hybrid transmission experiences during the course ofits typical travel, differing operating range states of the transmissionand engine states of the engine may at any time be viewed as beingadvantageous in consideration of an overall balance between such factorsincluding fuel economy, required torque output of the transmission, andstate of charge of the ESD 74. At any one instant in time, a particulartransmission operating range state and engine state may be desirable,advantageous or preferred, while at subsequent instants in time othertransmission operating range states and engine states may be desirable,advantageous or preferred, with the result being that over even arelatively short time span of operation such as, for example, fiveminutes, conditions making dozens or more desirable, advantageous, orpreferred transmission operating range states and engine states existduring such time span. However, this disclosure provides that alteringthe transmission operating range state and engine states in response toeach and every single change in operating conditions encountered is notnecessarily desirable in a motorized vehicle having anelectro-mechanical hybrid transmission.

FIG. 3 shows a control system architecture for controlling and managingsignal flow in a hybrid powertrain system having multiple torquegenerative devices, described hereinbelow with reference to the hybridpowertrain system of FIGS. 1 and 2, and residing in the aforementionedcontrol modules in the form of executable algorithms and calibrations.The control system architecture is applicable to alternative hybridpowertrain systems having multiple torque generative devices, including,e.g., a hybrid powertrain system having an engine and a single electricmachine, a hybrid powertrain system having an engine and multipleelectric machines. Alternatively, the hybrid powertrain system canutilize non-electric torque-generative machines and energy storagesystems, e.g., hydraulic-mechanical hybrid transmissions (not shown).

In operation, the operator inputs to the accelerator pedal 113 and thebrake pedal 112 are monitored to determine the operator torque request.The operator inputs to the accelerator pedal 113 and the brake pedal 112comprise individually determinable operator torque request inputsincluding an immediate accelerator output torque request (‘Output TorqueRequest Accel Immed’), a predicted accelerator output torque request(‘Output Torque Request Accel Prdtd’), an immediate brake output torquerequest (‘Output Torque Request Brake Immed’), a predicted brake outputtorque request (‘Output Torque Request Brake Prdtd’) and an axle torqueresponse type (‘Axle Torque Response Type’). As used herein, the term‘accelerator’ refers to an operator request for forward propulsionpreferably resulting in increasing vehicle speed over the presentvehicle speed, when the operator selected position of the transmissiongear selector 114 commands operation of the vehicle in the forwarddirection. The terms ‘deceleration’ and ‘brake’ refer to an operatorrequest preferably resulting in decreasing vehicle speed from thepresent vehicle speed. The immediate accelerator output torque request,the predicted accelerator output torque request, the immediate brakeoutput torque request, the predicted brake output torque request, andthe axle torque response type are individual inputs to the controlsystem. Additionally, operation of the engine 14 and the transmission 10are monitored to determine the input speed (‘Ni’) and the output speed(‘No’). The immediate accelerator output torque request is determinedbased upon a presently occurring operator input to the accelerator pedal113, and comprises a request to generate an immediate output torque atthe output member 64 preferably to accelerate the vehicle. The predictedaccelerator output torque request is determined based upon the operatorinput to the accelerator pedal 113 and comprises an optimum or preferredoutput torque at the output member 64. The predicted accelerator outputtorque request is preferably equal to the immediate accelerator outputtorque request during normal operating conditions, e.g., when any one ofantilock braking, traction control, or vehicle stability is not beingcommanded. When any one of antilock braking, traction control or vehiclestability is being commanded the predicted accelerator output torquerequest remains the preferred output torque with the immediateaccelerator output torque request being decreased in response to outputtorque commands related to the antilock braking, traction control, orvehicle stability control.

The immediate brake output torque request is determined based upon apresently occurring operator input to the brake pedal 112, and comprisesa request to generate an immediate output torque at the output member 64to effect a reactive torque with the driveline 90 which preferablydecelerates the vehicle. The predicted brake output torque requestcomprises an optimum or preferred brake output torque at the outputmember 64 in response to an operator input to the brake pedal 112subject to a maximum brake output torque generated at the output member64 allowable regardless of the operator input to the brake pedal 112. Inone embodiment the maximum brake output torque generated at the outputmember 64 is limited to −0.2 g. The predicted brake output torquerequest can be phased out to zero when vehicle speed approaches zeroregardless of the operator input to the brake pedal 112. When commandedby the operator, there can be operating conditions under which thepredicted brake output torque request is set to zero, e.g., when theoperator setting to the transmission gear selector 114 is set to areverse gear, and when a transfer case (not shown) is set to afour-wheel drive low range.

A strategic control scheme (‘Strategic Control’) 310 determines apreferred input speed (‘Ni_Des’) and a preferred engine state andtransmission operating range state (‘Hybrid Range State Des’) based uponthe output speed and the operator torque request and based upon otheroperating parameters of the hybrid powertrain, including battery powerlimits and response limits of the engine 14, the transmission 10, andthe first and second electric machines 56 and 72. The predictedaccelerator output torque request and the predicted brake output torquerequest are input to the strategic control scheme 310. The strategiccontrol scheme 310 is preferably executed by the HCP 5 during each 100ms loop cycle and each 25 ms loop cycle. The desired operating rangestate for the transmission 10 and the desired input speed from theengine 14 to the transmission 10 are inputs to the shift execution andengine start/stop control scheme 320.

The shift execution and engine start/stop control scheme 320 commandschanges in the transmission operation (‘Transmission Commands’)including changing the operating range state based upon the inputs andoperation of the powertrain system. This includes commanding executionof a change in the transmission operating range state if the preferredoperating range state is different from the present operating rangestate by commanding changes in application of one or more of theclutches C1 70, C2 62, C3 73, and C4 75 and other transmission commands.The present operating range state (‘Hybrid Range State Actual’) and aninput speed profile (‘Ni_Prof’) can be determined. The input speedprofile is an estimate of an upcoming input speed and preferablycomprises a scalar parametric value that is a targeted input speed forthe forthcoming loop cycle. The engine operating commands and theoperator torque request are based upon the input speed profile during atransition in the operating range state of the transmission.

A tactical control scheme (‘Tactical Control and Operation’) 330 isexecuted during one of the control loop cycles to determine enginecommands (‘Engine Commands’) for operating the engine 14, including apreferred input torque from the engine 14 to the transmission 10 basedupon the output speed, the input speed, and the operator torque requestcomprising the immediate accelerator output torque request, thepredicted accelerator output torque request, the immediate brake outputtorque request, the predicted brake output torque request, the axletorque response type, and the present operating range state for thetransmission. The engine commands also include engine states includingone of an all-cylinder operating state and a cylinder deactivationoperating state wherein a portion of the engine cylinders aredeactivated and unfueled, and engine states including one of a fueledstate and a fuel cutoff state. An engine command comprising thepreferred input torque of the engine 14 and the present input torque(‘Ti’) reacting between the engine 14 and the input member 12 arepreferably determined in the ECM 23. Clutch torques (‘Tcl’) for each ofthe clutches C1 70, C2 62, C3 73, and C4 75, including the presentlyapplied clutches and the non-applied clutches are estimated, preferablyin the TCM 17.

An output and motor torque determination scheme (‘Output and MotorTorque Determination’) 340 is executed to determine the preferred outputtorque from the powertrain (‘To_cmd’). This includes determining motortorque commands (‘T_(A)’, ‘T_(B)’) to transfer a net commanded outputtorque to the output member 64 of the transmission 10 that meets theoperator torque request, by controlling the first and second electricmachines 56 and 72 in this embodiment. The immediate accelerator outputtorque request, the immediate brake output torque request, the presentinput torque from the engine 14 and the estimated applied clutchtorque(s), the present operating range state of the transmission 10, theinput speed, the input speed profile, and the axle torque response typeare inputs. The output and motor torque determination scheme 340executes to determine the motor torque commands during each iteration ofone of the loop cycles. The output and motor torque determination scheme340 includes algorithmic code which is regularly executed during the6.25 ms and 12.5 ms loop cycles to determine the preferred motor torquecommands.

The hybrid powertrain is controlled to transfer the output torque to theoutput member 64 to react with the driveline 90 to generate tractivetorque at wheel(s) 93 to forwardly propel the vehicle in response to theoperator input to the accelerator pedal 113 when the operator selectedposition of the transmission gear selector 114 commands operation of thevehicle in the forward direction. Similarly, the hybrid powertrain iscontrolled to transfer the output torque to the output member 64 toreact with the driveline 90 to generate tractive torque at wheel(s) 93to propel the vehicle in a reverse direction in response to the operatorinput to the accelerator pedal 113 when the operator selected positionof the transmission gear selector 114 commands operation of the vehiclein the reverse direction. Preferably, propelling the vehicle results invehicle acceleration so long as the output torque is sufficient toovercome external loads on the vehicle, e.g., due to road grade,aerodynamic loads, and other loads.

FIG. 4 details signal flow in the strategic optimization control scheme310, which includes a strategic manager 220, an operating range stateanalyzer 260, and a state stabilization and arbitration block 280 todetermine the preferred input speed (‘Ni_Des’) and the preferredtransmission operating range state (‘Hybrid Range State Des’). Thestrategic manager (‘Strategic Manager’) 220 monitors the output speedNo, the predicted accelerator output torque request (‘Output TorqueRequest Accel Prdtd’), the predicted brake output torque request(‘Output Torque Request Brake Prdtd’), and available battery powerP_(BAT) _(—) _(MIN) to P_(BAT) _(—) _(MAX). The strategic manager 220determines which of the transmission operating range states areallowable, and determines output torque requests comprising a strategicaccelerator output torque request (‘Output Torque Request AccelStrategic’) and a strategic net output torque request (‘Output TorqueRequest Net Strategic’), all of which are input the operating rangestate analyzer 260 along with system inputs (‘System Inputs’) and powercost inputs (‘Power Cost Inputs’), and any associated penalty costs(‘Penalty Costs’) for operating outside of predetermined limits. Theoperating range state analyzer 260 generates a preferred power cost(‘P*cost’) and associated input speed (‘N*i’) for each of the allowableoperating range states based upon the operator torque requests, thesystem inputs, the available battery power and the power cost inputs.The preferred power costs and associated input speeds for the allowableoperating range states are input to the state stabilization andarbitration block 280 which selects the preferred operating range stateand preferred input speed based thereon. The operating range stateanalyzer 260 executes searches in each candidate operating range statecomprising the allowable ones of the operating range states, includingM1 (262), M2 (264), G1 (270), G2 (272), G3 (274), and G4 (276) todetermine preferred operation of the torque actuators, i.e., the engine14 and the first and second electric machines 56 and 72 in thisembodiment. The preferred operation preferably comprises a minimum powercost for operating the hybrid powertrain system and an associated engineinput for operating in the candidate operating range state in responseto the operator torque request. The associated engine input comprises atleast one of a preferred engine input speed (‘Ni*’), a preferred engineinput power (‘Pi*’), and a preferred engine input torque (‘Ti*’) that isresponsive to and preferably meets the operator torque request. Theoperating range state analyzer 260 evaluates M1-Engine-off (264) andM2-Engine-off (266) to determine a preferred cost (‘P*cost’) foroperating the powertrain system responsive to and preferably meeting theoperator torque request when the engine 14 is in the engine-off state.

FIG. 6 schematically shows signal flow for the 1-dimension search scheme610. A range of one controllable input, in this embodiment comprisingminimum and maximum input torques (‘TiMin/Max’), is input to a 1-Dsearch engine 415. The 1-D search engine 415 iteratively generatescandidate input torques (‘Ti(j)’) which range between the minimum andmaximum input torques, each which is input to an optimization function(‘Opt To/Ta/Tb’) 440, for n search iterations. Other inputs to theoptimization function 440 include system inputs preferably compriseparametric states for battery power, clutch torques, electric motoroperation, transmission and engine operation, the specific operatingrange state and the operator torque request. The optimization function440 determines transmission operation comprising an output torque, motortorques, and associated battery powers (‘To(j), Ta(j), Tb(j), Pbat(j),Pa(j), Pb(j)’) associated with the candidate input torque based upon thesystem inputs in response to the operator torque request for thecandidate operating range state. The output torque, motor torques, andassociated battery powers and power cost inputs are input to a costfunction 450, which executes to determine a power cost (‘Pcost(j)’) foroperating the powertrain in the candidate operating range state at thecandidate input torque in response to the operator torque request. The1-D search engine 415 iteratively generates candidate input torques overthe range of input torques and determines the power costs associatedtherewith to identify a preferred input torque (‘Ti*’) and associatedpreferred cost (‘P*cost’). The preferred input torque (‘Ti*’) comprisesthe candidate input torque within the range of input torques thatresults in a minimum power cost of the candidate operating range state,i.e., the preferred cost.

FIG. 7 shows the preferred operation in each of continuously variablemodes M1 and M2 executed in blocks 262 and 264 of the operating rangestate analyzer 260. This includes executing a 2-dimensional searchscheme 620, shown with reference to FIGS. 6 and 8, in conjunction withexecuting a 1-dimensional search using the 1-dimensional search scheme610 based upon a previously determined input speed which can bearbitrated (‘Input Speed Stabilization and Arbitration’) 615 todetermine preferred costs (‘P*cost’) and associated preferred inputspeeds (‘N*i’) for the operating range states. As described withreference to FIG. 8, the 2-dimensional search scheme 620 determines afirst preferred cost (‘2D P*cost’) and an associated first preferredinput speed (‘2D N*I’). The first preferred input speed is input to the2-dimensional search scheme 620 and to an adder. The adder sums thefirst preferred input speed and a time-rate change in the input speed(‘N_(I) _(—) _(DOT)’) multiplied by a predetermined time period (‘dt’).The resultant is input to a switch 605 along with the first preferredinput speed determined by the 2-dimensional search scheme 620. Theswitch 605 is controlled to input either the resultant from the adder orthe preferred input speed determined by the 2-dimensional search scheme620 into the 1-dimensional search scheme 610. The switch 605 iscontrolled to input the preferred input speed determined by the2-dimensional search scheme 620 into the 1-dimensional search scheme 610(as shown) when the powertrain system is operating in a regenerativebraking mode, e.g., when the operator torque request includes a requestto generate an immediate output torque at the output member 64 to effecta reactive torque with the driveline 90 which preferably decelerates thevehicle. The switch 605 is controlled to a second position (not shown)to input the resultant from the adder when the operator torque requestdoes not include regenerative braking. The 1-dimensional search scheme610 is executed to determine a second preferred cost (‘1D P*cost’) usingthe 1-dimensional search scheme 610, which is input to the input speedstabilization and arbitration block 615 to select a final preferred costand associated preferred input speed.

FIG. 8 schematically shows signal flow for the 2-dimension search scheme620. Ranges of two controllable inputs, in this embodiment comprisingminimum and maximum input speeds (‘NiMin/Max’) and minimum and maximuminput powers (‘PiMin/Max’), are input to a 2-D search engine 410. Inanother embodiment, the two controllable inputs can comprise minimum andmaximum input speeds and minimum and maximum input torques. The 2-Dsearch engine 410 iteratively generates candidate input speeds (‘Ni(j)’)and candidate input powers (‘Pi(j)’) which range between the minimum andmaximum input speeds and powers. The candidate input power is preferablyconverted to a candidate input torque (‘Ti(j)’) (412). Each candidateinput speed (‘Ni(j)’) and candidate input torque (‘Ti(j)’) are input toan optimization function (‘Opt To/Ta/Tb’) 440, for n search iterations.Other inputs to the optimization function 440 include system inputspreferably comprising parametric states for battery power, clutchtorques, electric motor operation, transmission and engine operation,the specific operating range state and the operator torque request. Theoptimization function 440 determines transmission operation comprisingan output torque, motor torques, and associated battery powers (‘To(j),Ta(j), Tb(j), Pbat(j), Pa(j), Pb(j)’) associated with the candidateinput power and candidate input speed based upon the system inputs andthe operating torque request for the candidate operating range state.The output torque, motor torques, and associated battery powers andpower cost inputs are input to a cost function 450, which executes todetermine a power cost (‘Pcost(j)’) for operating the powertrain at thecandidate input power and candidate input speed in response to theoperator torque request in the candidate operating range state. The 2-Dsearch engine 410 iteratively generates the candidate input powers andcandidate input speeds over the range of input speeds and range of inputpowers and determines the power costs associated therewith to identify apreferred input power (‘P*’) and preferred input speed (‘Ni*’) andassociated preferred cost (‘P*cost’). The preferred input power (‘P*’)and preferred input speed (‘N*’) comprises the candidate input power andcandidate input speed that result in a minimum power cost for thecandidate operating range state.

FIG. 9 schematically shows power flow and power losses through hybridpowertrain system, in context of the exemplary powertrain systemdescribed above. There is a first power flow path from a fuel storagesystem 9 which transfers fuel power (‘P_(FUEL)’) to the engine 14 whichtransfers input power (‘P_(I)’) to the transmission 10. The power lossin the first flow path comprises engine power losses (‘P_(LOSS ENG)’).There is a second power flow path which transfers electric power(‘P_(BATT)’) from the ESD 74 to the TPIM 19 which transfers electricpower (‘P_(IN ELEC)’) to the first and second electric machines 56 and72 which transfer motor power (‘P_(MOTOR MECH)’) to the transmission 10.The power losses in the second power flow path include battery powerlosses (‘P_(LOSS BATT)’) and electric motor power losses(‘P_(LOSS MOTOR)’). The TPIM 19 has an electric power load(‘P_(HV LOAD)’) that services electric loads in the system (‘HV Loads’),which can include a low voltage battery storage system (not shown). Thetransmission 10 has a mechanical inertia power load input(‘P_(INERTIA)’) in the system (‘Inertia Storage’) that preferablyinclude inertias from the engine 14 and the transmission 10. Thetransmission 10 has a mechanical power losses (‘P_(LOSS MECH)’) andpower output (‘P_(OUT)’) which can be affected by brake power losses(‘P_(LOSS BRAKE)’) when being transferred to the driveline in the formof axle power (‘P_(AXLE)’).

The power cost inputs to the cost function 450 are determined based uponfactors related to vehicle driveability, fuel economy, emissions, andbattery usage. Power costs are assigned and associated with fuel andelectrical power consumption and are associated with specific operatingpoints of the hybrid powertrain. Lower operating costs can be associatedwith lower fuel consumption at high conversion efficiencies, lowerbattery power usage, and lower emissions for each engine speed/loadoperating point, and take into account the candidate operating state ofthe engine 14. As described hereinabove, the power costs may include theengine power losses (‘P_(LOSS ENG)’), electric motor power losses(‘P_(LOSS MOTOR)’), battery power losses (‘P_(LOSS BATT)’), brake powerlosses (‘P_(LOSS BRAKE)’), and mechanical power losses (‘P_(LOSS MECH)’)associated with operating the hybrid powertrain at a specific operatingpoint which includes input speed, motor speeds, input torque, motortorques, a transmission operating range state and an engine state.

A preferred operating cost (P_(COST)) can be determined by calculating atotal powertrain system power loss P_(LOSS TOTAL) and a correspondingcost penalty. The total system power loss P_(LOSS TOTAL) comprises allpowertrain system power losses and includes the engine power lossesP_(LOSS ENG), electric motor power losses P_(LOSS MOTOR), battery powerlosses P_(LOSS BATT), brake power losses P_(LOSS BRAKE), and mechanicalpower losses P_(LOSS MECH).

The engine power loss in the engine 14 includes power losses due to fueleconomy, exhaust emissions, losses in the mechanical system (e.g.,gears, pumps, belts, pulleys, valves, chains), losses in the electricalsystem (e.g., wire impedances and switching and solenoid losses), andheat losses. The engine power loss can be determined for each operatingrange state based upon input speed and input torque and/or input speedand input power.

Thus, in fixed gear operation, i.e., in one of the fixed gear operatingranges states of G1, G2, G3 and G4 for the embodiment described herein,the power cost input comprising the mechanical power loss to the costfunction 450 can be predetermined outside of the 1-dimension searchscheme 610. In mode operation, i.e., in one of the mode operating rangesstates of M1 and M2 for the embodiment described herein, the power costinput comprising the mechanical power loss to the cost function 450 canbe determined during each iteration of the search scheme 620.

The state stabilization and arbitration block 280 selects a preferredtransmission operating range state (‘Hybrid Range State Des’) whichpreferably is the transmission operating range state associated with theminimum preferred cost for the allowed operating range states outputfrom the operating range state analyzer 260, taking into account factorsrelated to arbitrating effects of changing the operating range state onthe operation of the transmission to effect stable powertrain operation.The preferred input speed (‘Ni_Des’) is the engine input speedassociated with the preferred engine input comprising the preferredengine input speed (‘Ni*’), the preferred engine input power (‘Pi*’),and the preferred engine input torque (‘Ti*’) that is responsive to andpreferably meets the operator torque request for the selected preferredtransmission operating range state.

The cost information used in the cost function of each iteration loop insome embodiments comprises operating costs, in terms of energy usage,which are generally determined based upon factors related to vehicledrivability, fuel economy, emissions, and battery life for the operatingrange state. Furthermore, costs may be assigned and associated with fueland electrical power consumption associated with a specific operatingpoint of the powertrain system for the vehicle. Lower operating costsare generally associated with lower fuel consumption at high conversionefficiencies, lower battery power usage, and lower emissions for anoperating point, and take into account a current operating range stateof the powertrain system. The optimum operating cost (P_(COST)*) can bedetermined by calculating a total powertrain system loss, comprising anoverall system power loss and a cost penalty, such as can be associatedwith controlling battery state of charge. The overall system power losscomprises a term based upon engine power loss driven by fuel economy andexhaust emissions, plus losses in the mechanical system (e.g., gears,pumps, belts, pulleys, valves, chains), losses in the electrical system(e.g., wire impedances and switching and solenoid losses), and heatlosses. Other losses to be considered may include electrical machinepower losses, and factors related to battery life due to depth ofdischarge of the ESD 74, current ambient temperatures and their effecton state of charge of the battery. Due to subjective constraints imposedon a system such as that herein described, the transmission operatingrange state selected may not in all cases be that which is truly optimalfrom the standpoint of energy usage and power losses. At any one instantin time, a particular transmission operating range state and enginestate may be desirable, advantageous or preferred, while at subsequentinstants in time other transmission operating range states and enginestates may be desirable, advantageous or preferred, with the resultbeing that over even a relatively short time span of operation such as,for example, five minutes, conditions making dozens or more desirable,advantageous, or preferred transmission operating range states andengine states exist during such time span. However, this disclosureprovides that altering the transmission operating range state and enginestates in response to each and every single change in operatingconditions encountered is not necessarily desirable in a motorizedvehicle having an electro-mechanical hybrid transmission.

Given various operating conditions possible for a motorized vehicleequipped with an electro-mechanical hybrid transmission, which includevaried environmental and road conditions such as road grade and operatortorque demands, it is generally possible for an electro-mechanicalhybrid transmission to be usefully operatively engaged potentially inmore than one transmission operating range state, including such rangestates specified in Table I, at a given time during its operation.Moreover, it may be true that for every change in road grade,accelerator pedal position, and brake pedal depression that a motorizedvehicle including an electro-mechanical hybrid transmission experiencesduring the course of its typical travel, differing transmissionoperating range state and engine states of the engine may at any time beviewed as being advantageous in consideration of an overall balancebetween such factors including fuel economy, required torque output ofthe transmission, and state-of-charge of the ESD 74.

According to one embodiment of this disclosure, FIG. 10 shows a firstplurality of numerical values, each of which represents a preferabilityfactor for each of the potential operating range states of anelectro-mechanical hybrid transmission, and potential engine states forthe engine, including the operating range states and engine statesspecified in Table I. In FIG. 10, the designations M1 and M2 refer tomode 1 and mode 2 of the electro-mechanical hybrid transmission. Forpurposes of the disclosure, the term ‘candidate operating range state’can be used interchangeably with ‘potential operating range state’ andthe term ‘candidate engine state’ can be used interchangeably with‘potential engine state’. The designations G1, G2, G3, and G4 refer togear 1, gear 2, gear 3, and gear 4, respectively, and HEOff refers tothe engine state, which engine state is either engine-on or engine-off.In one embodiment of this disclosure, any one or more such preferabilityfactors may be arbitrarily assigned. In another embodiment, any one ormore of such preferability factors may comprise an output generated as aresult of any algorithmic or other data processing method which has asan input or basis any information provided by any one or more sensorsdisposed at any location on a motorized vehicle equipped with such anelectro-mechanical hybrid transmission, or disposed on, at, or near anyportion of its drive train where data may be acquired. Such sensors mayinclude without limitation: a wheel speed sensor 94, an output speedsensor 84, and a rotational speed sensor 11.

It is desired that the preferability factors provided for each of thetransmission operating range states and engine state shown in FIG. 10are maintained in association with their respective transmissionoperating range state and engine state, and according to one embodimentof this disclosure such preferability factors are set forth in an array,as shown in FIG. 10. This arrangement is not a strict requirement, butis of convenience when performing a method according to this disclosure,as shown and described in relation to FIG. 11.

This disclosure also provides a plurality of numerical values, each ofwhich is associated with one of the possible operating range states andengine states of an electro-mechanical hybrid transmission at anyselected point in time while in service in a motorized vehicle, such asduring operation while a vehicle is traveling on a road surface, whichplurality may be referred to as current operating range state values.Preferred embodiments include a numerical value associated with theengine state. This second plurality of numerical values are shownarranged in an array in FIG. 11 labeled as “current operating rangefactors” which includes numerical values for both the transmissionoperating range state and the engine state.

FIG. 11 illustrates how the numerical values of the first plurality ofpreferability factors from FIG. 10 may be combined with the secondplurality of preferability factors from the current operating rangestate and engine state. In one embodiment, the combination is made bysumming the numerical values from each corresponding operating rangestate and engine state in each array, to arrive at a third array thatcomprises preferability factors for each possible transmission operatingrange state and engine state, which is labeled “new desired operatingrange factors”. As used herein, a desired operating range state refersto a transmission operating range state or engine state that is, for onereason or another, generally relating to drivability, but may relate toengine economy, emissions or battery life, more desirable than thecurrent transmission operating range state and/or engine state. Thenumerical values present in the third array may be compared to oneanother, and in one embodiment the lowest numerical value present in thethird array represents the transmission operating range state or enginestate which is to be selected or evaluated for selection as a basis uponwhich to make a change in operating state of the electro-mechanicalhybrid transmission while a motorized vehicle containing same is inoperation. For example, in the third array in FIG. 11, the lowestnumerical value is 7, corresponding to M1 operation of theelectro-mechanical hybrid transmission, whereas the current operatingrange state for the transmission is M2, evidenced by the zero in thecurrent operating range array being the lowest numerical value. In oneillustrative, non-limiting exemplary embodiment, a signal would be sentto a shift execution module embedded in the TCM 17, suggesting a changeof transmission operating range state from M2 to M1, which may beeffected by the TCM. In alternate embodiments, the TCM may be providedwith additional decision-making data and algorithms to either accept andexecute a suggested command change resulting from a process according tothis disclosure, or it may deny such execution, based on other factorsprogrammed into the TCM 17 which can be arbitrary in one embodiment, andin other embodiments are based on the output of one or more algorithmshaving inputs provided by on-board vehicle sensors. In one embodiment ofthe disclosure, the TCM 17 provides current operating range factors,which may be in the same format that the numerical values for the secondplurality of preferability factors are in. In other embodiments, the TCM17 provides current operating range factors in any format different thanthat which the numerical values relating to the second plurality ofpreferability factors are in.

In another embodiment, the first plurality of preferability factorsdescribed in reference to FIG. 10 may be combined with an alternativeplurality of preferability factors, which are depicted in the arraylabeled as the “desired operating range factors” (which includenumerical values for both the transmission operating range state and theengine state) in FIG. 11, to arrive at a third array comprising a set ofpreferability factors which are considered the “new desired operatingrange factors”. The preferability factors comprising the desiredoperating range factors may be an output generated as a result of anyalgorithm or other data processing method of information provided by anyone or more sensors disposed at any location on a motorized vehicleequipped with such an electro-mechanical hybrid transmission, ordisposed on, at, or near any portion of its drive train where data maybe acquired. Such sensors include without limitation: a wheel speedsensor 94, an output speed sensor 84, and a rotational speed sensor 11.In another embodiment, the first plurality of preferability factorsdescribed in reference to FIG. 10 may be combined with both thepreferability factors from the current operating range factors and thedesired operating range factors to arrive at a third array comprisingnew desired operating range factors.

In general, one or more of the preferability factors among the desiredoperating range factors will change over time, in response to changingoperating conditions encountered by a motorized vehicle equipped with anelectro-mechanical hybrid transmission, and the value of these factorsmay either increase or decrease during vehicle operation. For example,when a operator torque request upon encountering an uphill grade whiletraveling at a low speed, the preferability factor associated with G1operation may be caused to decrease in value in response thereto.Similarly, when the vehicle operator makes a braking torque request uponencountering an downhill grade while traveling at a constant speed, thepreferability factor associated with G1 operation may be caused toincrease substantially in value so that selection of the G1 operatingrange is essentially precluded.

In FIG. 11, the numerical values in the arrays comprising the currentoperating range factors and the desired operating range factors areidentical only for illustrative purposes, and in practice the numericalvalues present in these sets of preferability factors may differ fromone another. For embodiments in which the first plurality ofpreferability factors from FIG. 10 are combined with those of thedesired operating range factors, a third array comprising preferabilityfactors for a new desired operating range factors are provided, at leastone of which factors are subsequently provided to a shift control modulewhich may be embedded in the TCM 17. For instances in which the shiftcontrol module orders the execution of a change in transmissionoperating range state, engine state, or both, the preferability factorscomprising the new desired operating range factors are communicated asan input to a process of this disclosure as the desired operating rangefactors in a subsequent iteration of a process as herein described, asit is desirable in such embodiments to repeatedly perform a method asdescribed herein at any time interval desired or selected, which may beany interval between about 2 milliseconds and about 300 milliseconds,including all intervals and ranges of intervals therebetween.

In preferred combinations of preferability factors according to thedisclosure, it is desirable to only combine preferability factors oflike kind with one another, i.e., preferability factors relating to M1may only be combined with other preferability factors which relate toM1, G2 with G2, and so forth. Although combination of arrays, each ofwhich comprise a plurality of preferability factors according to oneembodiment of this disclosure has been shown and described as involvingthe summation of such arrays, and selecting the least value present inan array as a value for consideration in making a change in theoperating range of an electro-mechanical hybrid transmission, thepresent disclosure also includes embodiments in which the selectioncriteria is to choose the largest numerical value. In other embodiments,the combination of two or more arrays may include subtraction, division,or multiplication of the numerical values corresponding to eachoperating range present in the arrays so combined, to provide that oneof the values emerges as unique or differentiable from the remainingvalues present as a result of such combination, each value representinga relative preferability of the engine state or transmission rangestate. Selection is then made basis the highest or lowest numericalvalue present, or any other differentiable numerical attribute, in eachof such embodiments. For cases where two or more preferability factorspresent in a set or array which results from a combination ofpreferability factors as provided herein are identical ornon-differentiable from one another, the selection of a transmissionoperating range from such non-differentiable values may be arbitrary, ormay be set to any default selection desired.

In one embodiment of the disclosure, the numerical values of the firstplurality of preferability factors in the array shown in FIG. 10 may beselected to be of a size sufficient to provide a biasing effect whencombined with numerical values present in either the desired operatingrange factors or current operating range factors as described inreference to FIG. 11. For convenience according to one embodiment, setsof such preferability factors from FIG. 10 may be provided and arrangedin a matrix, as shown in Table II and Table III below:

TABLE II Bias offset matrix for stabilization of current operating rangeDesired Range M1 M2 G1 G2 G3 G4 HEOff Current M1 0 0.5 A 0.5 0.5 0.5 0.5Range M2 0.5 0 0.1 0.1 0.2 0.5 0.2 G1 0.5 0.5 0   0.5 0.3 0.5 0.5 G2 0.30.1 0.5 0 0.5 0.3 0.2 G3 0.5 0.2 0.3 0.5 0 0.5 0.5 G4 0.5 0.5 0.5 0.20.5 0 0.5 HEOff 0.5 0.5 0.5 0.5 0.5 0.5 0Thus, a plurality of preferability factors for the current operatingrange factors may be provided from such matrix. Under such anarrangement, if the current operating range of the electro-mechanicalhybrid transmission is M1, then numerical values from the first row arechosen as the numerical values for the array to be used in a combinationof arrays as described herein. Arrays for the desired operating rangefactors may be selected from a matrix such as that shown in Table III,as representative of preferability factor values associated with thedesired operating range state of the electro-mechanical hybridtransmission and engine state.

TABLE III Bias offset matrix for stabilization of previously selecteddesired operating range Desired Range M1 M2 G1 G2 G3 G4 HEOff PreviouslyM1 0 0.5 B 0.5 0.5 0.5 0.5 Selected M2 0.5 0 0.1 0.1 0.2 0.5 0.2 DesiredG1 0.5 0.5 0 0.5 0.3 0.5 0.5 Range G2 0.3 0.1 0.5 0 0.5 0.3 0.2 G3 0.50.2 0.3 0.5 0 0.5 0.5 G4 0.5 0.5 0.5 0.2 0.5 0 0.5 HEOff 0.5 0.5 0.5 0.50.5 0.5 0

When combining arrays comprising current operating range factors anddesirable operating range factors described in reference to FIG. 11 witha plurality of preferability factors as provided in reference to FIG. 10according to this disclosure, the net effect is to stabilize theshifting of the transmission to both the desired operating range and thecurrent operating range by inclusion of the preferability factorsprovided according to FIG. 10. Through judicious selection of the valuesin Tables II and III above, an unexpected benefit arises in that it ispossible to select values which prohibit specific changes in operatingrange states of an electro-mechanical hybrid transmission. For example,a change in operating range from M2 to G4 may be permitted, whereas achange in operating range from M2 to G3 may be forbidden, the choices ofwhich changes to permit or forbid being in control of the user of amethod herein by their judicious selection of numerical values for thepreferability factors. In general, it is desirable to avoid selectingnon-allowed range states, whether based on output speed of thetransmission or any other criteria selected by a user. In oneembodiment, different potential input speeds for M1 and M2 operation ofthe transmission are considered over time in providing correspondingnumerical values for these states in the first plurality of numericalvalues, independent of the desired transmission operating range state.According to one embodiment, a selection process involves considerationonly of the input speed associated with the desired transmissionoperating state selected. In one preferred embodiment, the numericalvalue representative of the current transmission operating range statehas a bias of zero. In other embodiments, the numerical valuerepresentative of the current transmission operating range state has arelatively small bias, and may be either positive or negative. Althoughshown as positive numerical values, a preferability factor according tothe disclosure may be negative, since the net result of a process hereinwhich combines the different preferability factors for the resultspecified depends generally on their relative magnitudes with respect toone another.

The net effect of the stabilization of shifting events or changes ofoperating range of an electro-mechanical hybrid transmission accordingto this disclosure is illustrated in FIG. 12, which uses power loss asits ordinate; however, other units of ordinate may be employed asdesired. In FIG. 12 the power loss associated with vehicle operation inG1 over time of varying operating conditions is shown by the dotted wavyline. As this power loss varies along the abscissa of time labeled asM1, it may be possible for other operating range states of theelectro-mechanical hybrid transmission to be employed to advantage withrespect to fuel economy, battery state-of-charge, total torque output,etc. However, given typical wide variance in torque demands over time byan operator, a plurality of shifting or transmission mode changes wouldadversely impact drivability of a vehicle so equipped. Hence, by thepresent incorporation of bias, by consideration of the preferabilityfactors described, the power loss associated with vehicle operation inG1 over time of varying operating conditions may be moved upwards on theordinate scale, to the corresponding solid wavy line, the amount ofwhich bias is represented by the sum of factors A and B from the firstrow in Table II and Table III respectively. The result of this withreference to FIG. 12 is that the transmission operating range remains inM1 until the power loss associated with operating in that mode, plus thebias amount, exceeds the power loss of operating in another operatingrange state, in this case G1, at which point a change in operating rangestate is effected, with the power loss throughout the depicted timeinterval following the path marked by solid circles. Accordingly,situations where excessive operating range state changes of anelectro-mechanical hybrid transmission occur, are maintained at anydesirable level, dictated by the preferability factors chosen, which canmean their minimization, as well as substantial or complete elimination.This result is also depicted in FIG. 13, which shows the transmissiondesired operating range state as ordinate, depicting the removal of whatwould have been deemed as an undesirable operating range state changefor some end-use applications of a vehicle equipped with anelectro-mechanical hybrid transmission according to the disclosure.

In one embodiment, the matrices, arrays, or other arrangements ofpreferability factors as described herein are caused to be present in oraccessible to a microprocessor, in hard or soft memory, and thecombinations described herein are preferably carried out using such aprocessing device, which then issues an output to a TCM 17 that itselfemploys such output as an input in its own decision-making process.However, any arrangement of the preferability factors in memory which isconvenient for computing purposes may be employed, in addition to suchmatrices or arrays as herein described. Individual preferability factorsmay relate to, or be based upon any number of potential variablesrelating to vehicle operation, and include without limitation variablesrelating to energy usage, drivability, fuel economy, tailpipe emissions,and battery state-of-charge, with information concerning such variablesbeing provided in one embodiment, by sensors. In other embodiments, thepreferability factors may be derived from or based on losses in amechanical drive system, including losses due to belts, pulleys, valves,chains, losses in the electrical system, heat losses, electrical machinepower losses, internal battery power loses, or any other parasitic lossin a vehicle system, taken either alone, or in combination with any oneor more other loss or losses.

FIG. 14 depicts an architecture including a microprocessor, which iscapable of carrying out execution of a change of operating range stateof an electro-mechanical hybrid transmission according to one embodimentof the disclosure. FIG. 14 shows microprocessor MP, having inputs of thecurrent desired range preferability factors, and the preferabilityfactors described in reference to FIG. 10. The microprocessor has anoutput, which is inputted to a transmission control module, TCM 17,which itself provides feedback to the microprocessor in the form of aplurality of current operating range state preferability factors. TheTCM 17 is capable of providing a suggested shift execution command tothe transmission 10.

Operation of a vehicle equipped with an electro-mechanical hybridtransmission as herein described (including functionally-equivalentdevices) also includes the transmission input speed, N_(I), which itselfis subject to change as vehicle operating conditions encountered duringtravel of a motorized vehicle vary. After undergoing a change inoperating conditions, it is true that in many cases a differenttransmission operating range state may become more desirably employedthan the present or current transmission operating range state. Ingeneral, the transmission input speed N_(I) are different for differenttransmission operating range states possible when the motorized vehicleis traveling at the same given speed, when different operating modes ortransmission operating states are contemplated as being employed asalternate operative modalities for operating at a same given speed.Accordingly, a change in transmission operating state and/or enginestate is desirably accompanied by a change in transmission input speedN_(I).

FIG. 15 illustrates graphically one example of how the transmissioninput speed N_(I) may vary over time when a vehicle equipped with anelectro-mechanical hybrid transmission as herein described undergoes anexemplary change in operating range state from M1 to M2. The N_(I) forM1 represents the current N₁ when the current transmission operatingrange state is M1. G2 N_(I) and M2 N_(I) represent the selected(desired) N_(I) for the corresponding transmission operating rangestates. Since a direct change of operating range state from M1 to M2 isforbidden, the transmission must first pass through G2. During such atransition, the necessary transmission input speed N_(I) is seen tofirst decrease when going from M1 to G2, then to increase slightly overtime during brief operation in G2, after which a steep increase in N_(I)is experienced in achieving M2 operation. Therefore, the path or “trip”that the transmission input speed N_(I) is seen to go through is givenby:

(M1N_(I)−G2N_(I))+(M2N_(I)−G2N_(I))  [1]

in which M1 N_(I) is the transmission input speed for transmission M1operation; G2 N_(I) is the transmission input speed for transmission G2operation, M2 N_(I) is the transmission input speed for transmission M2operation, and G2 N_(I) is the transmission input speed for transmissionG2 operation. By weighting the direction of change of N_(I), the total“cost” of the trip that the transmission input speed is seen to gothrough can be provided by a calculation of the type:

TC=[(M1N _(I) −G2N _(I))*a+(M2N _(I) −G2N _(I))*b]*x  [2]

in which the “*” character indicates a multiplication operation, and aand b are constants in which a is used for negative changes in N_(I) andin which b is used for positive changes in N_(I). In alternateembodiments, a and b are varying parameters which are a function of thecorresponding distance of the N_(I) trip or the corresponding desiredtransmission operating range state. The variable x, a trip-directionweighting constant, is a subjective value which may be set or determinedby the vehicle engineers. The determination of x takes into accountwhether a potential change in transmission operating range state firstrequires a shift up followed by a shift down, or whether it firstrequires a shift down, followed by a shift up, as shown in FIG. 15. Ifthe required sequence is shift down, then shift up, then x is set to asubjectively-determined value c. If the required sequence is shift upthen shift down, the x is set to a subjectively-determined value d. Forthe case illustrated in FIG. 15, the formula for determining TC is:

TC=[(M1N _(I) −G2N _(I))*a+(M2N _(I) −G2N _(I))*b]*c  [3]

By analogous arithmetic a trip costing factor (TC) may be readilyprovided for every potential change in transmission operating rangestate and engine state by consideration of the trip that the N_(I) mustpass for a given potential change in transmission operating range stateand engine state at any point in time of the vehicle travel. Althoughthe changes in N_(I) shown in FIG. 15 follow a straight-line path forpurposes of illustration, in actual operation the changes in N_(I) mayalso follow curved paths during all or a portion of the transition,wherein the paths may be either concave-up or concave-down. As shown asoccurring at different points in time in FIG. 15, the calculation of theN_(I) values for M1, which in this example is the origin of the trip isthat of the monitored current N_(I) value, and the calculation of N_(I)values for G2 and M2 operation, which represent the intermediate andfinal destinations of the trip, may be conducted simultaneously.

FIG. 16 graphically illustrates how selected values of N_(I) may varyover time for each transmission operating range state shown during theoperation of a motorized vehicle equipped with an electro-mechanicalhybrid transmission as herein described. The current N_(I) profilerepresents the monitored current N_(I) values, which in this example iswhen the current transmission operating range state is M1. In oneembodiment, the selected N_(I) values (which may in alternateembodiments be desired N_(I) values or required N_(I) values) at variouspoints in time are arbitrarily selected to yield the curves shown. Inother embodiments the selected N_(I) values at various points in timeare based on the output of one or more algorithms having inputs providedby on-board vehicle sensors, which after manipulation such as by amicroprocessor may provide curves similar or different to those shown inFIG. 16. Importantly, as shown in FIG. 9, for each point in time T_(x)under consideration, there is associated with each of such curves asingle point, which may be used as a basis for calculating thedifferences in rpm, labeled “Δ rpm” which differences in rpm are usefulin determining a trip costing factor associated with every potentialchange in transmission operating range state for any desired point intime. While rpm is used herein to exemplify one implementation, otherrotational speed metrics are equally applicable. In one embodiment, theΔ rpm values may be conveniently set forth in an array as in Table IVbelow:

TABLE IV rpm difference values associated with potential changes intransmission operating range states. M1 M2 G1 G2 G3 G4 HEOff 0 Δ rpm 3 Δrpm 1 Δ rpm 3 Δ rpm 4 Δ rpm 5 Δ rpm 6 Δ rpm 2wherein the rpm differences associated with M2 involves the rpmdifference M1 to G2 and G2 to M2 as earlier described. The M1 N_(I)value used for the Δ rpm calculation is that of the current M1 N_(I)value and not that of the selected M1 N_(I) value. The values for the Δrpm in Table IV are exemplary of those encountered when the transmissionis presently in M1 operation, as the value of the Δ rpm for M1 is zero,which has a biasing effect that tends to maintain the transmissionoperating range state in M1, thus stabilizing the transmission operatingrange state with respect to M1 operation. In one embodiment, the valuesfor the Δ rpm associated with each potential change in transmissionoperating range state, such as those provided in Table IV, are each nextmultiplied by the trip direction weighting constants a, b, c, d (whichin alternate embodiments may be varying parameters which are a functionof the corresponding distance of the trip, Δ rpm, or correspondingdesired range) from the equation defining TC above for each associatedpotential change in transmission operating range state, to arrive at anew array comprising a plurality of Trips Costing factors (TC)representing preferability factors for each of the transmissionoperating range states that are effectively based on the input speedtrip or profile associated with each potential change in operating rangestate of the transmission, of which the values in Table V are providedfor exemplary purposes and are non-limiting of this disclosure:

TABLE V preferability factors based on transmission input speed N_(I)trip M1 M2 G1 G2 G3 G4 HEOff 0 0.6 0.3 0.4 0.5 0.7 0.8

The preferability factors based on the input speed trip or profile(“transmission input speed trip preferability factors”) associated witheach potential operating range state of the transmission as set forth inTable V may be combined as herein specified with other sets ofpreferability factors, including one or more sets of preferabilityfactors shown in and described with reference to FIG. 11 towardsgeneration of new desired operating range factors. The selected N_(I)values at various points in time as shown in FIG. 16 may be based on theoutput of one or more algorithms carried out in a microprocessor havingone or more inputs provided by on-board vehicle sensors, includingwithout limitation sensors mentioned herein. In some embodiments,transmission input speeds N_(I) for M1 operation and M2 operation areprovided at selected intervals with regard to the desired operatingrange state of the transmission. In one embodiment, the N_(I) value forM1 is selected by a microprocessor which searches and selects an N_(I)value that is associated with the least power loss, which in thisembodiment may serve as, or as a basis for determining the preferabilityfactor for M1 operation from FIG. 10. At or at about the same time, theN_(I) value for M2 operation is selected by a microprocessor whichsearches and selects an N_(I) value that is associated with the leastpower loss, which in this embodiment may serve as, or as a basis fordetermining the preferability factor for M2 operation from FIG. 10.Slight changes in operating conditions can substantially alter thepreferability factors, and could result in transmission operation thatwould attempt to change gears or modes too frequently, and the biasingor weighting of the preferability factors as herein described alleviatesundesirably frequent shifting. For embodiments in which N_(I) values forM1 and M2 are continuously provided at short time intervals on the orderof milliseconds in response to changes in vehicle operating conditions,given that slight changes in operating conditions can substantiallyalter the preferability factors, it occurs that there may be widefluctuations in the N_(I) values for M1 and M2 from one time interval tothe next. Changing operating range state for every instance that adriving condition changed slightly would result essentially in atransmission which was nearly constantly attempting to change gears ormodes, and the biasing or weighting of the preferability factors asherein described alleviates undesirably frequent shifting. Followinggeneration of new desired operating range factors and selection of thedesired operating range, the N_(I) values for the desired operatingrange are evaluated for selection and it is frequently the case that theN_(I) values may vary substantially from one interval to the next. It isaccordingly desirable to “filter” the N_(I) values, to remove noise,which noise comprises values that are very high above or below anaverage N_(I) value owing to instantaneous fluctuation in the N_(I)values during one or more short time intervals. In one embodiment, N_(I)values for both M1 operation, M2 operation and neutral are filtered,even though the values of only one of M1 or M2 are actually to be usedat a given point in time, i.e., the system continuously provides N_(I)values for both M1 and M2 operation. In such embodiment, while inputspeeds N_(I) for M1 or M2 operation are provided continuously or atselected intervals, only the input speed N_(I) associated with thedesired mode (either M1 or M2) is used for creating a desiredtransmission input speed profile based on current vehicle operatingconditions. After selection of a desired range state is made, theselected N_(I) values for M1 and M2 are filtered to reduce noise, whilefiltering, when the desired range changes reset the filter of the modeof the desired range that it is transitioning to, in order that theinitial output value is equivalent to the input value, as shown in FIG.18. The suggested N_(I) values depicted therein will eventually be usedto create a profile of desired input speeds based on what range isdesired. For example, when M1 is selected as the desired range, N_(I) M1is used as the desired N_(I) profile, as soon as M2 becomes desired theprofile will switch to suggested N_(I) M2. This selective resetting isdone so that when the system switches from one profile to another, thenon-filtered suggested N_(I) is used as the initial value. Whenfiltering the suggested input speeds for noise reduction, only thesuggested input speed of the desired mode is filtered. This allows thesuggested input speed to reset when its mode is chosen.

One consideration of operating a motorized vehicle that is equipped withan electro-mechanical hybrid transmission as described herein, is thatthe operator of such a motorized vehicle will at different times makedifferent torque requests from the drivetrain (such as by depressing thevehicle accelerator or brake pedal). However, in many instances ofoperator torque requests, the vehicle drivetrain and/or braking systemmay be incapable of delivering the amount of torque requested by theoperator, i.e., the brake or accelerator pedal may be depressed beyondthe point at which the system capabilities to deliver the requestedtorque can be fulfilled. An accelerator pedal is one non-limiting formof an accelerator control.

For different potential engine operating points in operating rangestates of the transmission, given the same operator torque request, thedifferences between the operator-requested torque and the vehicledrivetrain capabilities typically differ from one another. In oneembodiment of this disclosure, the difference between the amount oftorque requested by the operator at a given point in time and the torquethat is deliverable by the system when operating at a potential engineoperating point is considered for each of the engine operating points,to generate a plurality of torque difference values for each of theengine operating points at substantially the time that the operatormakes a torque request. In one embodiment a biasing “cost” value isassigned to each of the torque difference values in proportion to themagnitude by which the deliverable torque for a given engine operatingpoint in a potential transmission operating range state falls short withrespect to that of the operator torque request. Such biasing cost valuesgenerally reflect a lower degree of desirability for engine operatingpoints having higher biasing costs associated with them for a givenoperator torque request, when such biasing costs are compared with oneanother and used as a basis in evaluating which engine operating pointis most suitable or desirable for a given operator torque request at aparticular point in time of the vehicle operation. In one embodiment,the sum of all components representing power losses for variousdrivetrain components and this bias cost (comprising the total powerloss) for each potential engine operating point at the torquedeliverable that is nearest to that requested by the operator arecompared with one another, with that potential engine operating pointhaving the least total power loss when operated at the torque nearestthat of the operator torque request being selected as the desired engineoperating point.

FIG. 19 shows a cost function useful in providing biasing costsindicating a component of preferability of a potential engine operatingpoint and transmission operating range state, which is dependent on themagnitude of an operator torque request. The exemplary definition of abiasing cost graph in FIG. 19 is a generally-parabolic cost profile,having as its abscissa the operator torque request. Such a biasing costprofile may be determined by any function desired, selected, or createdby the vehicle engineers, and accordingly affords an opportunity toinclude a subjective aspect in the determination of preferability ofdifferent engine operating points and potential transmission operatingrange states. Function types useful in this regard include withoutlimitation: hyperbolic functions, linear functions, continuousfunctions, non-continuous functions, constant functions, smooth-curvedfunctions, circular functions, ovoid functions, and any combinationscomprising any of the foregoing, either alone or mathematically combinedwith one another, over any range of operator torque request valuesdesired or selected. Thus, in one embodiment, criteria used in thedetermination of which engine operating point and transmission operatingrange state is most desirable for a given operator torque request at anyselected point in time of the travel of a vehicle having a drivetrain asherein described is not necessarily bound to the most efficientoperation of the motorized vehicle in terms of fuel economy, poweroutput, drivability, etc.

For each engine operating point in a potential transmission operatingrange state, there exists a minimum output torque (T_(O) Min) and amaximum output torque (T_(O) Max) that the drivetrain system is capableof delivering. The maximum output torque is generally applicable towardsvehicle acceleration and includes such components as the engine inputtorque and motor torques from the first and second electric machines.The minimum output torque is generally applicable towards vehicledeceleration, and includes such components as braking torque providedduring regenerative braking, including cases when the charging of abattery on-board the vehicle is accomplished, more or less, by one ormore of the electric machines functioning in their capacity aselectrical generators.

With respect to FIG. 19, which represents a single engine operatingpoint in a potential transmission operating range state, it is clearthat for a substantial range of possible operator torque request valuesresiding between T_(O) Min and T_(O) Max, there is no biasing costassociated therewith, i.e., the value of the function represented by thedotted line is zero. As the operator torque request approaches orexceeds the T_(O) Max value, however, the cost associated with theoperator torque request is given by the ordinate value along the dottedline curve corresponding to the operator torque request. Other potentialtransmission operating range states may have the same, similarly-shaped,or differently-shaped functions associated with them, as desired.

In one embodiment, if the operator torque request is within a rangebetween T_(O) Min and T_(O) Max where the biasing cost functionrepresented by the dashed line curve in FIG. 19 is constant, in thiscase at zero, there is no biasing cost assigned for the particularengine operating point in the operating range state under considerationat levels of operator torque request residing within this range. Whenthe operator torque request is for a torque that is greater than T_(O)Max, the function determining the biasing costs associated with thetorque request is represented by the dashed line in FIG. 11. Thisbiasing cost may thus comprise a subjective component in addition to theobjective costs associated with power losses in the determination of theengine operating point selection and the first plurality of numericalvalues shown in FIG. 10. Thus, in one embodiment, an operator torquerequest which only slightly exceeds that of T_(O) Max, by, for example,10 Newton-meters, will be assigned a biasing cost which is less than thebiasing cost which would be assigned to an operator torque request whichexceeds that of T_(O) Max by more than 10 Newton-meters.

Table VI below is exemplary of one way to express costs associated withthe difference between a vehicle operator torque request and the maximumtorque deliverable by the drivetrain system for an exemplary potentialtransmission operating range state, wherein Δ N*m is the differencevalue in Newton-meters and kW is the cost, expressed in kilowatts inthis example; however any other convenient units, or no units, may beused. Such an array may be stored in computer memory and accessed by amicroprocessor, on an as-needed basis.

TABLE VI Costs assigned for different torque requests for a potentialtransmission operating range state Δ N * m 0 10 100 1000 kW 0 20 50180,000

An alternative representation of the biasing cost associated with apotential transmission operating range state is shown in FIG. 20. InFIG. 20, the value x represents the difference between the amount ofoperator torque request and that torque output which is desirable(“Desirable T_(O)”) for a potential transmission operating range state,as but one example. The Desirable T_(O) is that amount of torque that isclosest to the operator torque request that is available based on theoutput torque limits (T_(O) Max and T_(O) Min) of the selected engineoperating points and the Torque Reserve for the particular potentialtransmission operating range state under consideration. The quantity x,which is a torque difference value (Δ N*m), varies, depending on whichpotential transmission operating state is under consideration, for thesame operator torque request at a same given point in time of vehicleoperation. Comparison of x values for different potential transmissionoperating range states given the same operator torque request enablesselection of that potential transmission operating range state havingthe least x value, in one embodiment. In another embodiment, a biasingcost (weighting factor) may be assigned to the potential transmissionoperating range state having the least x value, which is combined withthe sum of all components representing power losses for variousdrivetrain components, to arrive at a sum total power loss which maythen be used as a criteria for selecting a particular potentialtransmission operating range state over others.

By providing a function having any desired features, including withoutlimitation those features illustrated by the biasing costs curve in FIG.19, it is possible to assign a biasing cost to a given operator torquerequest for particular instances even when the torque requested in anoperator torque request is below the maximum system torque output. Thisis illustrated by an operator torque request having the magnitude atpoint Q in FIG. 19, which is below the T_(O) Max, yet there isnevertheless a cost assigned for this potential transmission operatingrange state and operator torque request. Such a provision of costing (orbiasing) operator torque requests allows establishment of a TorqueReserve over the range of operator torque requests which reside betweenT_(O) Max and the operator torque request having the highest magnitudeof torque for which no biasing cost is assigned over a range betweenT_(O) Min and T_(O) Max. The provision of a range of operator torquerequests comprising such a Torque Reserve effectively biases thepreferability of the transmission control system against selectingsystem actuator operating points and transmission operating range stateshaving a T_(O) Max which is greater than, yet near to, an operatortorque request in an amount that is proportional to the differencebetween the operator torque request and the T_(O) Max for the particularengine operating point in a transmission operating range state underconsideration. Instead of biasing to select system actuator operatingpoints which can produce the highest T_(O) Max and lowest T_(O) Min,including the Torque Reserve has the effect of decreasing the biascriteria point T_(O) Max to T_(O) Max subtracted by the Torque Reserve.This will not only effect the operator torque requests which exceed themaximum deliverable output torque, but also the operator torque requeststhat are less than and near the maximum deliverable output torque. Thisresults in improved drivability of the motorized vehicle by reducing thetendency of the transmission system to cause multiple shifting events ormode changes when an operator torque request has a magnitude that isnear the maximum deliverable for the transmission operating range statethat is currently selected, i.e., currently under utilization. Inembodiments which follow, no Torque Reserve is present.

Moreover, when an operator torque request exceeds T_(O) Max (or is lessthan T_(O) Min) for cases where a method according to this disclosurewhich so uses biasing costs is not employed, information relating to theamount by which an operator torque request exceeds T_(O) Max (or is lessthan T_(O) Min) is lost due to the fact that the total power lossevaluation is based on the deliverable output torque which is limited byT_(O) Max and T_(O) Min. Proceeding in accordance with a method of thisdisclosure and obtaining a biasing cost value for an operator torquerequest which exceeds T_(O) Max (or is less than T_(O) Min) providesinformation relative to the amount by which such a torque request is inexcess of T_(O) Max, and this information is incorporated into theoverall selection process concerning which engine operating point andpotential transmission operating state will be selected. In oneembodiment, this information effectively biases a search engine embeddedwithin software and/or hardware useful for providing the plurality ofnumerical values shown in FIG. 10 to locate an engine operating pointwithin each potential transmission operating range state that biasestowards providing the greatest value of T_(O) Max (least value of T_(O)Min). In one embodiment, the biasing costs associated with the operatortorque request for each of the potential operating range states of thetransmission substantially at the time an operator makes a torquerequest during vehicle operation are but one component used indetermining a first plurality of numerical values as shown in FIG. 10.

In one embodiment, the calculation of each of the numerical valuespresent in the first plurality of numerical values shown in FIG. 10include components relating to objective power losses such as: enginepower loss, battery power loss, electrical machine power loss, andtransmission power loss. Another embodiment provides additional penaltycosts, including costs for exceeding the battery power limits, enginetorque limits, electric machine torque limits, and other subjectivecosts desired which may include biasing costs associated with the outputtorque request as herein described. Also included are the componentsgenerated as the result of an iterative data processing method that inone embodiment employs a microprocessor-based search engine.

A search engine suitable for such a method employs, for eachcontinuously variable operating range state, a space that is defined asshown in FIG. 21 by the region on the coordinate axes bounded by P_(I)Min, P_(I) Max, N_(I) Min, and N_(I) Max, wherein P_(I) represents powerinputted to the electro-mechanical hybrid transmission and N_(I) is thesame transmission input speed. The search engine selects, eitherrandomly or according to any desired algorithm, an N_(I) and P_(I) pairpresent in the space S and calculates a T_(O) Min, T_(O) Max and totalpower loss associated with the N_(I) and P_(I) pair chosen, based ondrivetrain system component power losses and operating constraints,which constraints are either inherent in the system, or imposed byvehicle engineers. Repetition of this method for a large number ofdifferent N_(I) and P_(I) pairs provides a plurality of different T_(O)Min, T_(O) Max and total power loss values for a given potentialcontinuously variable transmission operating range state from whichN_(I) and P_(I) pairs from each potential continuously variabletransmission operating state. The method is repeated for each potentialtransmission operating range state and a plurality of T_(O) Min, T_(O)Max, and total power loss values are generated in the space S of and foreach potential transmission operating range state and N_(I) and P_(I)pairs provided.

From such plurality of different T_(O) Min and T_(O) Max values sogenerated by a search engine for a given potential transmissionoperating range state, the N_(I) and P_(I) pair having the highest T_(O)Max value associated with each potential transmission operating rangestate is biased to be selected as the preferred N_(I) and P_(I), toreduce biasing costs associated with the output torque request in FIG.19, which is one of the multiple components in the total power loss,when an operator torque request is greater than the plurality ofdifferent T_(O) Max values generated. For cases in which an operatortorque request is less than the plurality of different T_(O) Mingenerated, the N_(I) and P_(I) pair associated with the lowest T_(O) Minvalue is biased to be selected as the preferred N_(I) and P_(I) toreduce biasing costs associated with the output torque request in FIG.19, which is one of the multiple components in the total power loss forthe particular potential transmission operating range state underconsideration. The hybrid Engine-Off state can be considered ascontinuously variable modes with the N_(I) and P_(I) as being zero;thus, T_(O) Min, T_(O) Max, and the total power loss are determinedwithout the need for a search procedure.

In the case of Fixed Gear range states, a search engine suitable forsuch a method employs, for each potential transmission operating rangestate, a space that is defined by the region on the coordinate axesbounded by T_(I) Min, and T_(I) Max, wherein T_(I) represents torqueinputted to the electro-mechanical hybrid transmission where thetransmission input speed is pre determined by the hardware parameter ofpotential transmission operating range state. The search engine selects,either randomly or according to any desired algorithm, an T_(I) presentin the search range and calculates a T_(O) Min and T_(O) Max and TotalPower Loss associated with the T_(I) chosen, based on drivetrain systemcomponent power losses and operating constraints, which constraints areeither inherent in the system, or imposed by vehicle engineers.Repetition of this method for a large number of different T_(I) providesa plurality of different T_(O) Min and T_(O) Max and Total Power Lossvalues for a given potential transmission operating range state. Themethod is repeated for each potential transmission operating range stateand a plurality of T_(O) Min and T_(O) Max and Total Power Loss aregenerated in the search range of and for each potential transmissionoperating range state and T_(I) is provided.

From such plurality of different T_(O) Min and T_(O) Max values sogenerated by a search engine for a given potential transmissionoperating range state, the T_(I) having the highest T_(O) Max valueassociated with each potential transmission operating range state isbiased to be selected as the preferred T_(I), when an operator torquerequest is greater than the plurality of different T_(O) Max generated.This reduces biasing costs associated with the output torque request inFIG. 19, which is one of the components in the total power loss for theparticular potential transmission operating range state underconsideration. For cases in which an operator torque request is lessthan the plurality of different T_(O) Min generated, the T_(I)associated with the lowest T_(O) Min value is biased to be selected asthe preferred T_(I) to reduce biasing costs associated with the outputtorque request in FIG. 19, which is one of the components in the totalpower loss for the particular potential transmission operating rangestate under consideration.

In one embodiment, including when a vehicle operator makes a request foran acceleration torque that is greater than the maximum deliverableoutput torque, following generation of a plurality of engine operatingpoints (N_(I) and P_(I) pairs for continuously variable modes and T_(I)for fixed gears) for each potential transmission operating range state,which engine operating points (N_(I) and P_(I) pairs for continuouslyvariable modes and T_(I) for fixed gears) each have associated with thema T_(O) Min, T_(O) Max, and total power loss values, the desiredtransmission operating range state is determined by comparing the pointsassociated with the selected engine operating points (N_(I) and P_(I)pairs for continuously variable modes and T_(I) for fixed gears) fromeach potential transmission operating state with one another, andselecting that operating range state having the least total power lossassociated with its point biased to the highest T_(O) Max value, whichcorresponds to the least value of x in FIG. 20.

In another embodiment, including when a vehicle operator makes a requestfor a deceleration torque that is less than the minimum deliverableoutput torque, following generation of a plurality of engine operatingpoints (N_(I), P_(I) pairs for continuously variable modes and T_(I) forfixed gears) for each potential transmission operating range state,which engine operating points (N_(I), P_(I) pairs for continuouslyvariable modes and T_(I) for fixed gears) each have associated with thema T_(O) Min, T_(O) Max, and total power loss values, the desiredtransmission operating range state is determined by comparing the pointsassociated with the selected engine operating points (N_(I) and P_(I)pairs for continuously variable modes and T_(I) for fixed gears) fromeach potential transmission operating state which have the least totalpower loss with one another and selecting that operating range statehaving the least total power loss associated with its point biased tohaving the lowest T_(O) Min value (corresponding to the least value of yin FIG. 20).

In one embodiment, determination of the total power loss associated withvehicle operation at a point associated with or identified by an engineoperating point (N_(I) and P_(I) pair for continuously variable modesand T_(I) for fixed gears) in a potential operating range state of thetransmission comprises combining operating costs, in terms of energyusage (kW), which operating costs are provided based upon factorsrelated to vehicle drivability, fuel economy, emissions, electricalpower consumption and battery life for the operating range state. Loweroperating costs are generally associated with lower fuel consumption athigh conversion efficiencies, lower battery power usage, and loweremissions for an operating point, and take into account a currentoperating range state of the powertrain system.

Summation of all power losses (total power loss) associated withoperating at a particular point that is associated with an engineoperating point (N_(I), P_(I) pair for continuously variable modes andT_(I) for fixed gears) of a potential transmission operating range stateprovides a preferability factor (including without limitation, thoseshown in FIG. 10) for operating at that particular point in theparticular potential transmission operating range state underconsideration. In the case when the operator torque request is greaterthan the torque deliverable by the driveline system, the pointassociated with an engine operating point (N_(I), P_(I) pairs forcontinuously variable modes and T_(I) for fixed gears) in the respectivesearch space S or range associated with a potential transmissionoperating range state may be selected to be biased to a point at whichthe maximum output torque (T_(O) Max) of the transmission occurs forthat potential transmission operating range state. Depending on theseverity of the bias cost associated with the operator torque request,the selected point may or may not be that at which the maximum outputtorque occurs. Since the point selection is based on minimizing thetotal power loss where the bias cost associated with the output torquerequest is a component of, the larger the bias costs associated with theoutput torque request the greater is the advantage of selecting thepoint at which the maximum output torque of the transmission occurs. Thesearch space S or range for each potential transmission operating rangestate may be examined, such as by algorithm, and the point associatedwith an engine operating point (N_(I), P_(I) pair for continuouslyvariable modes and T_(I) for fixed gears) at which the maximum outputtorque (T_(O) Max) of the transmission is biased to occur identified foreach potential transmission operating range state. The points associatedwith the engine operating point (N_(I), P_(I) pair for continuouslyvariable modes and T_(I) for fixed gears) at which the maximum outputtorque (T_(O) Max) of the transmission is biased to occur for eachpotential transmission operating range state are compared with oneanother to identify the potential transmission operating range statehaving the lowest power loss that is likely to have the highest T_(O)Max, which potential transmission operating range state is selected asbeing the best transmission operating range state when a vehicleoperator makes a request for an acceleration torque, which is a torquerequest that tends to deliver more torque to the vehicle drive wheel(s)that are in contact with the road surface.

Similarly, in the case when the operator torque request is less than thetorque deliverable by the driveline system, the point associated with anengine operating point (N_(I), P_(I) pair for continuously variablemodes and T_(I) for fixed gears) associated with a potentialtransmission operating range state may be selected to be biased to apoint at which the minimum output torque (T_(O) Min) of the transmissionoccurs for that potential transmission operating range state. Dependingon the severity of the bias cost associated with the operator torquerequest, the point selected may or may not be that at which the minimumoutput torque occurs. Since the point selection is based on minimizingthe total power loss where the bias cost associated with the outputtorque request is a component of, the larger the bias costs associatedwith the output torque request the more advantage there is to selectingthe point at which the minimum output torque of the transmission occurs.The search space S, or range for each potential transmission operatingrange state may be examined, such as algorithmically using amicroprocessor, and the point associated with an N_(I) and P_(I) pair atwhich the minimum output torque (T_(O) Min) of the transmission isbiased to occur identified for each potential transmission operatingrange state. The points associated with the engine operating point(N_(I), P_(I) pair for continuously variable modes and T_(I) for fixedgears) at which the minimum output torque (T_(O) Min) of thetransmission is biased to occur for each potential transmissionoperating range state are compared with one another to identify thepotential transmission operating range state having the lowest totalpower loss which is likely to have the lowest T_(O) Min, which potentialtransmission operating range state is selected as being the besttransmission operating range state when a vehicle operator makes arequest for an deceleration torque, which is a torque request that tendsto deliver less torque to the vehicle drive wheel(s) that are in contactwith the road surface.

According to one embodiment of this disclosure, for cases of operatortorque requests which command heavy vehicle acceleration (levels ofacceleration for which the operator torque request is greater than thatdeliverable by the driveline system and the pre-determined bias costassociated with the output torque request is severe enough to overruleall other components of the total power loss), determining the engineoperating point (N_(I), P_(I) pair for continuously variable modes andT_(I) for fixed gears) having the least power loss associated with themautomatically results in determination of the N_(I) and P_(I) pairhaving the T_(O) Max, because the engine operating point (N_(I), P_(I)pair for continuously variable modes and T_(I) for fixed gears) havingthe highest T_(O) Max values associated with it, also has the smallestpower losses associated with it. The converse is true for cases ofoperator torque requests which command vehicle deceleration.

Hence, in a method according to an embodiment of the disclosure, anoperator torque request is made during operation of a vehicle equippedwith a system as herein described. A search engine embedded in anon-board microprocessor chooses a first engine operating point (N_(I),P_(I) pair for continuously variable modes and T_(I) for fixed gears)from the search space S or range associated with a potentialtransmission operating range state. T_(O) Max and T_(O) Min valuesassociated with that engine operating point (N_(I), P_(I) pair forcontinuously variable modes and T_(I) for fixed gears) in the searchspace S or range are calculated. Then, the power losses associated withthat engine operating point (N_(I), P_(I) pair for continuously variablemodes and T_(I) for fixed gears) in the respective search space S orrange are calculated. As part of the total power loss calculation, thedifference between the operator torque request and the T_(O) Max (orT_(O) Min, as may be applicable for cases where deceleration torque isrequested) is assigned a biasing cost. This process is repeated for eachengine operating point (N_(I) and P_(I) pair for continuously variablemodes and T_(I) for fixed gears) in the space S or range chosen by thesearch algorithm associated with that potential transmission operatingrange state, which results in a cost being associated with each chosenengine operating point (N_(I), P_(I) pair for continuously variablemodes and T_(I) for fixed gears) in the respective search space S orrange associated with that potential transmission operating range state.The points having the lowest biasing costs are inherently inclined tohave the highest T_(O) Max and lowest T_(O) Min values.

Thus, a method according to the disclosure is concerned with balancingselection of a transmission operating range state from a set ofpotential transmission operating range states between choosing engineoperating point (N_(I), P_(I) pair for continuously variable modes andT_(I) for fixed gears, with emphasis on the N_(I) value, which is usedfor creating a desired transmission input profile as earlier describedherein) in the respective search space S or range which have the leastpower losses of the system associated with each potential transmissionoperating range state, which includes a bias cost that biases the pointselection to a point which has the highest T_(O) Max, (or lowest T_(O)Min). Preference in some embodiments may be given to those engineoperating point (N_(I), P_(I) pair for continuously variable modes andT_(I) for fixed gears) within the respective search space S or range forthe various potential transmission operating range states which have theabsolute least total power losses, which includes large bias costsassociated with the output torque request, which in such instance ismore concerned with meeting an extreme torque request from the vehicleoperator. In other embodiments, preference may be given to those engineoperating points (N_(I), P_(I) pairs for continuously variable modes andT_(I) for fixed gears) within the respective search space S or range forthe various potential transmission operating range states which have theabsolute least total power losses, which include none or small biascosts associated with the output torque request, as this is an instancewherein it is desired to focus less on attempting to meet the extremetorque demand of the driver, and more on overall system efficiency. Thechoice between whether preference is given to system performance to meetthe extreme torque demand as closely as possible, or to maximize theoverall system efficiency is controllable by altering the function whichdetermines the shape of the biasing cost curve shown in FIG. 19. Whenthe slope of the curve defined by the function therein is selected to besteeper, more weight is given to meeting the operator torque requestthat is higher or lower than the torque output deliverable by thedriveline.

Once a method of the disclosure has been used to identify whichpotential transmission operating range state is to be selected, thetransmission input speed N_(I) that was the basis for the selection ofthat particular transmission operating range state is used as thetransmission input speed for continuously variable modes.

It has been demonstrated that an operating point described by aparticular N_(I), P_(I) pair is caused to be selected from a searchrange space in view of power losses associated with one or more costfunctions, for the case of operation in modes such as M1 and M2.However, it may in certain instances, depending on the structure of thecost function(s) employed and operating conditions encountered, bepossible that the search method fails to converge to the N_(I), P_(I)pair associated with the lowest total power loss. For example, in someinstances this may be due to the nature of the costing functions andoperating conditions, eddies or areas on the cost function curve(s)having local minima may cause an iterative search method using a searchengine as herein described to zero-in on one N_(I), P_(I) pairassociated with a local minimum associated with a power loss that isgreater than that of the global minimum, such as that shown in exemplaryFIG. 22, instead of the global minimum that is defined by a differentN_(I), P_(I) pair. In such instances it may be considered that thesearch for an appropriate N_(I), P_(I) pair has then failed, whichfailure may become problematic with regards to stable operation of anelectro-mechanical transmission as provided herein. However, even forsome cases where the search does not so “fail” it may be desirable toensure that the N_(I) value that is chosen has good subjective appeal tothe operator. For instance, it might be that in some instances when aperson who is operating a vehicle equipped with a driveline as hereindescribed depresses the accelerator pedal, that an N_(I) value is chosenwhich is lower than that which was in use prior to the depression of theaccelerator pedal. In general, vehicle operators are accustomed tohearing a vehicle engine increase in rpm when they depress anaccelerator pedal and hearing or sensing a decrease in N_(I) inparticular instances may provide an undesirable, un-natural feeling to avehicle operator, which situation is desirably avoided.

In one embodiment a method as provided herein examines N_(I) values froma previous iteration of the search engine and makes a determination ofwhether a prior N_(I) value is more desirable, in terms of power loss,than a newly-generated N_(I) value from the search engine. For thosecases where it is found that the search “failed”, the prior N_(I) valuemay be chosen by Arbitration over the newly-generated N_(I) value,causing the general shape of the graph of the N_(I) value over time toappear as shown in FIG. 23, being constant over the region(s) where thesearch fails and the 1-dimensional (1D) search engine predominates the2-dimensional (2D) search engine results. In general, the Arbitrationwill examine the output of the 1D and 2D search engines and choose thatoutput having the least power loss associated with it.

In other embodiments, input speed (N_(I)) stabilization is enhanced byadding a cost to the existing cost function(s) or providing a separatecost function which stabilizes N_(I) to the position of the vehicleaccelerator pedal.

The disclosure provides an improved value for N_(I) in those cases wherethe search fails, by considering the rate of change of the input speed(N_(I)) expressed as d(N_(I))/dt. In one embodiment, an improved N_(I)value is provided the equation:

newN _(I)=oldN _(I) +[d(N _(I))/dt](dt)  [4]

(wherein “old N_(I)” refers to the N_(I) selected from the previoussearch, and d(N_(I))/dt refers to the optimal input speed change ratewhich are predetermined parameters which are dependent on the operatortorque request and driving conditions. These parameters represent adesired optimal input speed change rate and may be based on simulatedresults of the 2D search process for various operator torque requestsand driving conditions) and the N_(I)/time profile is also manipulated,based on accelerator pedal position by adding costs for those situationsin which the N_(I) profile over time is moving in a direction which isdeemed undesirable, based on subjective features determined by thevehicle engineers. This has the net effect of costing, and hence makingless favorable from the standpoint of selection, undesirable movementsin the N_(I) profile over time. Thus, according to a general case asprovided herein, the trajectory of the input speed that is chosen to bemost desirable, which may be called Opt N_(I), is stabilized byreplacing the 2-dimensional search optimal input speed (2D Opt N_(I))with the sum of the optimal input speed from the previous loop (OptN_(I) old) and the optimal input speed change rate, multiplied by thetime interval between search loops [d(N_(I))/dt](dt), as shownpictorially in FIG. 24, in which the following equalities apply:

2DOptN _(I)=2DN _(I)*  [5]

1DOptNI=1DNI*  [6]

2DOptPwrLoss=2DPCost*  [7]

1DOptPwrLoss=1DPCost*  [8]

in which OptN_(I) is the Arbitrated N_(I)*, and OptPwrLoss is theArbitrated PCost*). With reference to FIG. 25, one exemplary algorithmuseful for determining N_(I) is:

If  2D OptCost > 1D OptCost (*)   OptNi = OptNi_old + [d(N_(I))/dt] (dt)  OptPwrLoss = 1D OptPwrLoss Else   OptNi = 2D OptNi   OptPwrLoss = 2DOptPwrLoss −       (Driver pedal filter derivative gain schedulingcosting)(**) Endin which the 2D Optimal Cost could have a higher cost than the 1DOptimal Cost due to a relatively high driver pedal filter derivativegain scheduling cost, or when the 2D Search fails to converge to theminimum optimal cost. Driver pedal filter derivative gain schedulingcosting provides a cost the input speed change with respect to thedriver pedal aggressiveness, i.e cost heavy decrease (increase) in inputspeed when the driver pedal is requesting aggressive acceleration(deceleration). This is included in the Cost Function in the 2D and 1DOptimization for Input Speed stabilization purposes, but subtracted fromthe total cost arbitration so that it would not affect the optimal rangeselection. This cost is always 0 in the 1D Optimization sinceNi(j)=Ni_old.

In one embodiment, whether a movement in the N_(I) profile over time isdesirable or not is based on the position of the accelerator pedal. Inanother embodiment, whether a movement in the N_(I) profile over time isdesirable or not is based on the rate of change of position of theaccelerator pedal. However, in general, it is undesirable that the N_(I)value should decrease when the accelerator pedal is depressedsubstantially.

Referring now to FIG. 25 which illustrates a costing algorithm fornegative N_(I) changes (i.e., costing transmission input speed (N_(I))points that have a lower value than the selected N_(I) value from theprior search) the derivative of pedal position is along the x-axis inthe gain and offset functions. When the derivative of the pedal positionis negative, the cost gain and offset, which are the y-axis values ofthe cost gain and offset functions, are zero. This includes the casewhen the operator removes their foot from the accelerator pedal.

On the other hand, if the derivative of pedal position is positive, suchas when the vehicle operator depresses the accelerator pedal, then thecost gain and offset functions will not be zero, but will be given by:

${{{Accel}.\mspace{14mu} {Pedal}}\mspace{14mu} {Stabalizing}\mspace{14mu} {Cost}} = \mspace{59mu} {\begin{bmatrix}{\left( {{negative}\mspace{14mu} {gain}} \right)*} \\\left( {\Delta \mspace{11mu} N_{I}} \right)\end{bmatrix} + {{{neg}.\mspace{14mu} {offset}}\mspace{14mu} {value}}}$

These provisions ensure, in general, that if the N_(I) value isdecreasing with time at a given instant, costing will only occur whenthe operator depresses the accelerator pedal.

Referring now to FIG. 26, illustrating the costing algorithm forpositive N_(I) changes, i.e., costing transmission input speed (N_(I))points that have a higher value than the selected N_(I) value from theprior search, the derivative of pedal position is along the x-axis inthe gain and offset functions. When the derivative of the pedal positionis positive, the cost gain and offset, which are the y-axis values ofthe cost gain and offset functions, are zero. This includes the casewhen the operator depresses the accelerator pedal. On the other hand, ifthe derivative of pedal position is negative, such as when the operatorremoves their foot from the accelerator pedal, then the cost gain andoffset functions will not be zero, but will be given by the equation:

${{{Accel}.\mspace{14mu} {Pedal}}\mspace{14mu} {Stabalizing}\mspace{14mu} {Cost}} = \mspace{59mu} {\begin{bmatrix}{\left( {{positive}\mspace{14mu} {gain}} \right)*} \\\left( {\Delta \mspace{11mu} N_{I}} \right)\end{bmatrix} + {{{pos}.\mspace{14mu} {offset}}\mspace{14mu} {value}}}$

These provisions ensure, in general, that if the N_(I) value isincreasing with time at a given instant, this type of costing will onlyoccur when the operator removes their foot from the accelerator pedal.The negative, positive gain and offset values are subjective to thevehicle engineer, to enable latitude in providing enhanced drivabilityversus vehicle performance or economy.

In one embodiment, the processes described by FIGS. 25 and 26 areembedded in the cost functions (450) of the 1D and 2D process 610, 620,as shown and described in reference to FIGS. 6 and 8, and are but one ofa plurality of costs provided by cost functions and algorithms residentin those processes, and are conducted only with regards to thatoperating range state which is currently selected. Thus, the processinvolving stabilization of the N_(I) values as a function of pedalposition is not considered as a factor in selection of whichtransmission operating range state is to be selected at a given timegiven particular operator torque requests or operating parameters,including road conditions. In one embodiment, when preferability factorsare determined for purposes of determining transmission operating rangestate selection, the costs associated with stabilization of N_(I) aresubtracted out from the total costs used in determining thepreferability factors, as earlier described herein.

It is understood that modifications are allowable within the scope ofthe disclosure. The disclosure has been described with specificreference to the preferred embodiments and modifications thereto.Further modifications and alterations may occur to others upon readingand understanding the specification. It is intended to include all suchmodifications and alterations insofar as they come within the scope ofthe disclosure.

1. Method for improving drivability of a powertrain system having anaccelerator control and including an engine coupled to anelectro-mechanical transmission selectively operative in one of aplurality of transmission operating range states and one of a pluralityof engine states, comprising: determining a first transmission inputspeed, said first transmission input speed having an associated firstpower loss; operating said transmission using said first transmissioninput speed; determining an operational parameter relating to saidaccelerator control; determining a second transmission input speedresponsive to said operational parameter, said second transmission inputspeed having an associated second power loss; biasing the value of atleast one of said first and second power loss based on said operationalparameter; comparing said first power loss to said second power losssubsequent to said biasing; determining a third transmission inputspeed; and operating said transmission using said third transmissioninput speed.
 2. A method according to claim 1 wherein said operationalparameter comprise the position of said accelerator control.
 3. A methodaccording to claim 1 wherein said operational parameter comprises therate of change of position of said accelerator control.
 4. A methodaccording to claim 3, in which said rate of change of position of saidaccelerator control is substantially zero, and said biasing is omitted.5. A method according to claim 1 wherein determining a thirdtransmission input speed is based on the comparison of said first powerloss to said second power loss subsequent to said biasing.
 6. A methodaccording to claim 1 wherein said second transmission input speedresponsive to said operational parameter is determined using the rate ofchange of position of said accelerator control as a function of time. 7.A method according to claim 1 wherein biasing the value of at least oneof said first and second power loss is carried out using a costfunction.
 8. A method according to claim 7 wherein said cost functionincludes a gain component and an offset component.
 9. A method accordingto claim 1 in which said first power loss is determined to be less thansaid second power loss, and said first transmission input speed isselected as a new input speed at which to operate said transmission at afuture point in time.
 10. A method according to claim 1 in which saidthird transmission input speed is less than said second transmissioninput speed.
 11. A method according to claim 1 in which said thirdtransmission input speed is greater than said second transmission inputspeed.
 12. A method according to claim 1 in which said thirdtransmission input speed is greater than said second transmission inputspeed by an amount equal to about the product of [d(transmission inputspeed)/dt] and [dt], in which dt is any amount of time between about oneand about one thousand milliseconds, including all amounts of time andall intervals therebetween.
 13. Method for controlling a powertrainsystem including an engine having an accelerator control, said enginecoupled to an electro-mechanical transmission selectively operative inone of a plurality of transmission operating range states and one of aplurality of engine states, comprising: determining a currenttransmission operating range state and engine state; determining atleast one potential transmission operating range state and engine state;providing an operator torque request; determining preferability factorsassociated with the current transmission operating range state andengine state, and potential transmission operating range states andengine states; preferentially weighting the preferability factors forthe current transmission operating range state and engine state;selectively commanding changing the transmission operating range stateand engine state based upon said preferability factors and said operatortorque request; and stabilizing an input speed to said transmission,responsive to changes in a position of said accelerator control.